Sample records for 1996-2012 noyes mn

  1. ,"Noyes, MN Natural Gas Pipeline Imports From Canada (MMcf)"

    U.S. Energy Information Administration (EIA) Indexed Site

    Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Noyes, MN...

  2. Noyes, MN Natural Gas Exports to Canada

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto ChinaThousandDecade Year-0 Year-1(Million CubicLease8190 0 3,975

  3. 2, 431468, 2002 Adsorption of NOy

    E-Print Network [OSTI]

    Boyer, Edmond

    ACPD 2, 431­468, 2002 Adsorption of NOy on ice T. Bartels et al. Title Page Abstract Introduction Geophysical Society 2002 Atmospheric Chemistry and Physics Discussions The adsorption of nitrogen oxides (markus.ammann@psi.ch) 431 #12;ACPD 2, 431­468, 2002 Adsorption of NOy on ice T. Bartels et al. Title Page

  4. Noyes, MN Natural Gas Imports by Pipeline from Canada

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto ChinaThousandDecade Year-0 Year-1(Million CubicLease8190 0

  5. Noyes, MN Natural Gas Pipeline Exports to Canada (Million Cubic Feet)

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for On-Highway4,1,50022,3,,,,6,1,9,1,50022,3,,,,6,1,Decade1 Source: Office(BillionYear Jan Feb(Billion CubicProvedDecade Year-0

  6. Noyes, MN Natural Gas Pipeline Imports From Canada (Million Cubic Feet)

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for On-Highway4,1,50022,3,,,,6,1,9,1,50022,3,,,,6,1,Decade1 Source: Office(BillionYear Jan Feb(Billion CubicProvedDecade

  7. Noyes, MN Natural Gas Pipeline Exports to Canada (Million Cubic Feet)

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto ChinaThousandDecade Year-0 Year-1(Million CubicLease8190

  8. Noyes, MN Natural Gas Pipeline Imports From Canada (Million Cubic Feet)

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 111 1,613 122 40 Buildingto ChinaThousandDecade Year-0 Year-1(Million

  9. Noyes, MN Natural Gas Pipeline Exports to Canada (Dollars per Thousand

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug Sep Oct(Dollars819andCubic

  10. Noyes, MN Natural Gas Pipeline Exports to Canada (Dollars per Thousand

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug Sep

  11. Noyes, MN Natural Gas Pipeline Exports to Canada (Million Cubic Feet)

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug SepDecade Year-0 Year-1

  12. Noyes, MN Natural Gas Pipeline Imports From Canada (Dollars per Thousand

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug SepDecade Year-0 Year-1Cubic

  13. Noyes, MN Natural Gas Pipeline Imports From Canada (Dollars per Thousand

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug SepDecade Year-0

  14. Noyes, MN Natural Gas Pipeline Imports From Canada (Million Cubic Feet)

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5 Tables July 1996 Energy Information Administration Office ofthroughYear Jan Feb Mar Apr May Jun Jul Aug SepDecade Year-0Decade

  15. Highly Active Yeast MnSOD has a Novel Mechanism Involving Six-coordinate Mn(3+) Species

    E-Print Network [OSTI]

    Sheng, Yuewei

    2012-01-01T23:59:59.000Z

    2009) Functional roles of the tetramer organization of malicGrez, M. (2010) Dimer-tetramer transition controls RUNX1/ETOdimer, Å) Mn•••Mn (A/C, tetramer, Å) Mn•••Mn (A/D, tetramer,

  16. Structure and magnetic properties of rf thermally plasma synthesized Mn and MnZn ferrite nanoparticles

    E-Print Network [OSTI]

    McHenry, Michael E.

    Structure and magnetic properties of rf thermally plasma synthesized Mn and Mn­Zn ferrite has previously been shown to be a viable route to producing nanocrystalline magnetite and Ni ferrite nanoparticles. In this work nanocrystalline powders of Mn and Mn­Zn ferrites have been synthesized using a 50 k

  17. Effect of Mn Concentration on the Structural, optical and Magnetic Properties of GaMnN

    SciTech Connect (OSTI)

    Thaler, G.; Frazier, R.; Gila, B.; Stapleton, J.; Davidson, M.; Abernathy, C.R.; Pearton, S.J.; Segre, C.U. (IIT); (Florida)

    2010-11-16T23:59:59.000Z

    The room temperature magnetization of GaMnN films grown by molecular beam epitaxy on (0001) sapphire substrates with Mn concentrations varying from 0 to 9 at. % was found to depend on Mn concentration, with a maximum magnetization found at -3 at. % Mn. High-resolution x-ray diffraction measurements show that the c-plane lattice constant initially decreases with increasing Mn concentration, then increases when the Mn content increases above -3 at. %. This increase is accompanied by a decrease in the full width at half maximum of the rocking curves. Extended x-ray absorption fine structure results indicate that the nonsubstitutional Mn is not present in the form of Ga{sub x}Mn{sub y} clusters and thus is most likely present in the form of an interstitial. Optical absorption measurements show only a slight increase in the band gap for material with 3 at. % Mn, relative to undoped GaN.

  18. Structural And Physical Characterization of Tetranuclear [Mn**II(3)Mn**IV] And [Mn**II(2)Mn**III(2)] Valence-Isomer Manganese Complexes

    SciTech Connect (OSTI)

    Zaleski, C.M.; Weng, T.-C.; Dendrinou-Samara, C.; Alexiou, M.; Kanakaraki, P.; Hsieh, W.-Y.; Kampf, J.; Penner-Hahn, J.E.; Pecoraro, V.L.; Kessissoglou, D.P.

    2009-05-28T23:59:59.000Z

    Two tetranuclear Mn complexes with an average Mn oxidation state of +2.5 have been prepared. These valence isomers have been characterized by a combination of X-ray crystallography, X-ray absorption spectroscopy, and magnetic susceptibility. The Mn{sup II}{sub 3}Mn{sup IV} tetramer has the Mn ions arranged in a distorted tetrahedron, with an S = 6 ground spin state, dominated by ferromagnetic exchange among the manganese ions. The Mn{sup II}{sub 2}Mn{sup III}{sub 2} tetramer also has a distorted tetrahedral arrangement of Mn ions but shows magnetic behavior, suggesting that it is a single-molecule magnet. The X-ray absorption near-edge structure (XANES) spectra for the two complexes are similar, suggesting that, while Mn XANES has sufficient sensitivity to distinguish between trinuclear valence isomers (Alexiou et al. Inorg. Chem. 2003, 42, 2185), similar distinctions are difficult for tetranuclear complexes such as that found in the photosynthetic oxygen-evolving complex.

  19. Thermal Stability of MnBi Magnetic Materials. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    because Mn is easy to react with oxygen. MnO formation is irreversible and causes degradation to the magnetic properties. In this paper, we report our effort on developing MnBi...

  20. Effect of Mn doping on the structural, morphological, optical...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mn doping on the structural, morphological, optical and magnetic properties of indium tin oxide films. Effect of Mn doping on the structural, morphological, optical and magnetic...

  1. IMPROVEMENT OF CdMnTe DETECTOR PERFORMANCE BY MnTe PURIFICATION

    SciTech Connect (OSTI)

    Kim, K.H.; Bolotnikov, A.E.; Camarda, G.S.; Tappero, R.; Hossain, A.; Cui, Y.; Yang, G.; Gul, R.; and James, R.B.

    2011-04-25T23:59:59.000Z

    Residual impurities in manganese (Mn) are a big obstacle to obtaining high-performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material's purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te, which has a very high solubility for most impurities. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiply-refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.

  2. Co layer thickness dependence of exchange biasing for IrMnCo and FeMnCo

    E-Print Network [OSTI]

    Reilly, Anne

    Co layer thickness dependence of exchange biasing for IrMnÕCo and FeMnÕCo K. A. Seua) and H. Huang) in IrMn/Co and FeMn/Co bilayers using the magneto-optical Kerr effect. Samples are sputtered wedges on silicon with Co thicknesses ranging from 1 to 17 nm. The IrMn/Co with exchange bias interface energy of 0

  3. High Mn austenitic stainless steel

    DOE Patents [OSTI]

    Yamamoto, Yukinori (Oak Ridge, TN) [Oak Ridge, TN; Santella, Michael L (Knoxville, TN) [Knoxville, TN; Brady, Michael P (Oak Ridge, TN) [Oak Ridge, TN; Maziasz, Philip J (Oak Ridge, TN) [Oak Ridge, TN; Liu, Chain-tsuan (Knoxville, TN) [Knoxville, TN

    2010-07-13T23:59:59.000Z

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  4. Energy absorption in Ni-Mn-Ga/ polymer composites

    E-Print Network [OSTI]

    Feuchtwanger, Jorge

    2006-01-01T23:59:59.000Z

    In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

  5. Theory of weak localization in ferromagnetic (Ga,Mn)As

    E-Print Network [OSTI]

    Garate, Ion; Sinova, Jairo; Jungwirth, T.; MacDonald, A. H.

    2009-01-01T23:59:59.000Z

    We study quantum interference corrections to the conductivity in (Ga,Mn)As ferromagnetic semiconductors using a model with disordered valence-band holes coupled to localized Mn moments through a p-d kinetic-exchange interaction. We find that at Mn...

  6. Mn/DOT's Project Peer Review

    E-Print Network [OSTI]

    Minnesota, University of

    and sustain this culture #12;Project Management #12;Recent National Work in Transportation Project ManagementMn/DOT's Project Management Peer Review Creating a Project Management Culture 2010 CTS Research a Peer Review? Why Project Management? ·Improve project delivery performance ­ on time, on budget (an

  7. MN4602 Crouch 2004 REASSESSING WEAPON SYSTEM

    E-Print Network [OSTI]

    MN4602 Crouch 2004 REASSESSING WEAPON SYSTEM OPERATIONAL TEST & EVALUATION METHODOLOGIES LTC Thom support assessing a weapon systems true cost and performance characteristics? S1: Can/should cost, operational effectiveness and suitability be assessed independent of one another? S2: Do current test

  8. Influence of interstitial Mn on magnetism in room-temperature ferromagnet Mn(1+delta)Sb

    SciTech Connect (OSTI)

    Taylor, Alice E [ORNL; Berlijn, Tom [ORNL; Hahn, Steven E [ORNL; May, Andrew F [ORNL; Williams, Travis J [ORNL; Poudel, Lekhanath N [ORNL; Calder, Stuart A [ORNL; Fishman, Randy Scott [ORNL; Stone, Matthew B [ORNL; Aczel, Adam A [ORNL; Cao, Huibo [ORNL; Lumsden, Mark D [ORNL; Christianson, Andrew D [ORNL

    2015-01-01T23:59:59.000Z

    We report elastic and inelastic neutron scattering measurements of the high-TC ferromagnet Mn(1+delta)Sb. Measurements were performed on a large, TC = 434 K, single crystal with interstitial Mn content of delta=0.13. The neutron diffraction results reveal that the interstitial Mn has a magnetic moment, and that it is aligned antiparallel to the main Mn moment. We perform density functional theory calculations including the interstitial Mn, and find the interstitial to be magnetic in agreement with the diffraction data. The inelastic neutron scattering measurements reveal two features in the magnetic dynamics: i) a spin-wave-like dispersion emanating from ferromagnetic Bragg positions (H K 2n), and ii) a broad, non-dispersive signal centered at forbidden Bragg positions (H K 2n+1). The inelastic spectrum cannot be modeled by simple linear spin-wave theory calculations, and appears to be significantly altered by the presence of the interstitial Mn ions. The results show that the influence of the int

  9. Evidence of N substitution by Mn in GaN

    E-Print Network [OSTI]

    Pereira, LMC; Decoster, S; Correia, JG; da Silva, MR; Vantomme, A; Araújo, JP

    2012-01-01T23:59:59.000Z

    We report on the lattice location of Mn in wurtzite GaN using beta? emission channeling. In addition to the majority substituting for Ga, we locate up to 20% of the Mn atoms in N sites. We propose that the incorporation of Mn in N sites is enabled under sufficiently high concentrations of N vacancies, and stabilized by a highly charged state of the Mn cations. Since N substitution by Mn impurities in wurtzite GaN has never been observed experimentally or even considered theoretically before, it challenges the current paradigm of transition metal incorporation in wide-gap dilute magnetic semiconductors.

  10. Unexpected crystal and magnetic structures in MnCu4In and MnCu4Sn

    SciTech Connect (OSTI)

    Provino, A.; Paudyal, D.; Fornasini, ML; Dhiman, I.; Dhar, SK.; Das, A.; Mudryk, Y.; Manfrinetti, P.; Pecharsky, VK

    2013-01-29T23:59:59.000Z

    We discovered a new compound MnCu4In with its own hexagonal structure type (hP12-P63mc, ternary ordered derivative of the hexagonal MgZn2-type) that becomes ferromagnetic at TC = 540 K. This transition temperature is higher than that found in the MnCu2In and MnCu2Sn alloys. In contrast, the homologous compound MnCu4Sn, which crystallizes in the cubic MgCu4Sn-type, orders antiferromagnetically with TN = 110 K. The neutron diffraction studies show ferromagnetic spin orientation in the {1 0 1} plane in MnCu4In with a magnetic moment of 4.5 ?B/Mn at 22 K, and a corresponding value of 4.7 ?B/Mn in the antiferromagnetic MnCu4Sn with propagation vector View the MathML source. The first-principles electronic structure calculations show that the unexpected difference in both magnetic and crystal structures of MnCu4In and MnCu4Sn is due to the difference in the Mn-3d bands and exchange interactions relating to different crystal anisotropy, coordination numbers, and interatomic distances.

  11. ,"International Falls, MN Natural Gas Pipeline Imports From Canada...

    U.S. Energy Information Administration (EIA) Indexed Site

    International Falls, MN Natural Gas Pipeline Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of...

  12. ,"Warroad, MN Natural Gas Pipeline Imports From Canada (MMcf...

    U.S. Energy Information Administration (EIA) Indexed Site

    Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Warroad, MN...

  13. Polarized x-ray spectroscopy of quaternary ferromagnetic semiconductor (Ga,Mn)(As,P)

    E-Print Network [OSTI]

    Wadley, P.

    2011-01-01T23:59:59.000Z

    quaternary diluted magnetic semiconductor (Ga,Mn)(As,P) as aIn diluted magnetic semiconductors such as (Ga,Mn)As, whichquaternary diluted magnetic semiconductors such as (Ga,Mn)(

  14. Alignment of micro-crystals of Mn12-acetate and direct observation of single molecules thereof

    E-Print Network [OSTI]

    Seo, Dongmin

    2009-05-15T23:59:59.000Z

    This dissertation focuses on three separate studies. First, magnetization of the Mn12- acetate was studied by low temperature hysteresis loops and DC magnetization data on magnetically aligned Mn12-acetate micro-crystals. Secondly, Mn12-acetate thin...

  15. Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

    SciTech Connect (OSTI)

    Deng Rui; Zhou Hang; Qin Jieming; Wan Yuchun; Jiang Dayong; Liang Qingcheng [School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Li Yongfeng [Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012 (China); Wu, Tom [Physical Sciences and Engineering Division, Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Yao Bin [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Liu Lei [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No.3888 Dongnanhu Road, Changchun 130033 (China)

    2013-07-21T23:59:59.000Z

    Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn{sup 2+} and substituted for Zn (Mn{sub Zn}) in ZTO:Mn. This conclusion was supported by first-principles calculations. Mn{sub Zn} in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (Mn{sub Sn}). The nearest neighbor Mn{sub Zn} in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results.

  16. Minnesota Guidestar www.dot.state.mn.us/guidestar

    E-Print Network [OSTI]

    Minnesota, University of

    .dot.state.mn.us/guidestar What is ITS? · Application of technology to improve the safety and efficiency of the transportation system. #12;Minnesota Guidestar www.dot.state.mn.us/guidestar What is ITS? · Traffic Management ­ Signal Systems ­ Ramp Meters · Emergency Response ­ Mobile Data Terminals ­ 911 Dispatch ­ RF Data Networks

  17. Magnetic Moment Enhancement for Mn7 Cluster on Graphene

    SciTech Connect (OSTI)

    Liu, Xiaojie [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Lin, Hai-Qing [Beijing Computational Science Research Center; Ho, Kai-Ming [Ames Laboratory

    2014-08-21T23:59:59.000Z

    Mn7 cluster on graphene with different structural motifs and magnetic orders are investigated systematically by first-principles calculations. The calculations show that Mn7 on graphene prefers a two-layer motif and exhibits a ferrimagnetic coupling. The magnetic moment of the Mn7 cluster increases from 5.0 ?B at its free-standing state to about 6.0 ?B upon adsorption on graphene. Mn7 cluster also induces about 0.3 ?B of magnetic moment in the graphene layer, leading to an overall enhancement of 1.3 ?B magnetic moment for Mn7 on graphene. Detail electron transfer and bonding analysis have been carried out to investigate the origin of the magnetic enhancement.

  18. Spectroscopy of Mn atoms isolated in solid {sup 4}He

    SciTech Connect (OSTI)

    Moroshkin, P., E-mail: petr.moroshkin@riken.jp; Lebedev, V.; Weis, A. [Department of Physics, University of Fribourg, Chemin du Musée 3, 1700 Fribourg (Switzerland)

    2014-06-07T23:59:59.000Z

    We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to those of an inner-shell transition in Ba studied earlier. At the same time, they are more strongly perturbed than the corresponding transitions in Au and Cu under the same conditions. We suggest a qualitative explanation of these observations based on the atomic bubble model. Our results also suggest that the inner-shell transitions of Mn in solid He are more strongly perturbed than the same lines of Mn isolated in solid Ar or Kr matrices.

  19. Chemical and structural investigation of the role of both Mn and Mn oxide in the formation of manganese silicate barrier layers on SiO{sub 2}

    SciTech Connect (OSTI)

    Casey, P.; Bogan, J.; Hughes, G. [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Lozano, J. G.; Nellist, P. D. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2011-09-01T23:59:59.000Z

    In this study, Mn silicate (MnSiO{sub 3}) barrier layers were formed on thermally grown SiO{sub 2} using both metallic Mn and oxidized Mn films, in order to investigate the role of oxygen in determining the extent of the interaction between the deposited Mn and the SiO{sub 2} substrate. Using x-ray photoelectron spectroscopy, it has been shown that a metallic Mn film with an approximate thickness of 1 nm cannot be fully converted to Mn silicate following vacuum annealing to 500 deg. C. Transmission electron microscopy (TEM) analysis suggests the maximum MnSiO{sub 3} layer thickness obtainable using metallic Mn is {approx}1.7 nm. In contrast, a {approx}1 nm partially oxidized Mn film can be fully converted to Mn silicate following thermal annealing to 400 deg. C, forming a MnSiO{sub 3} layer with a measured thickness of 2.6 nm. TEM analysis also clearly shows that MnSiO{sub 3} growth results in a corresponding reduction in the SiO{sub 2} layer thickness. It has also been shown that a fully oxidized Mn oxide thin film can be converted to Mn silicate, in the absence of metallic Mn. Based on these results it is suggested that the presence of Mn oxide species at the Mn/SiO{sub 2} interface facilitates the conversion of SiO{sub 2} to MnSiO{sub 3}, in agreement with previously published studies.

  20. Magnetic coupling in neutral and charged Cr{sub 2}, Mn{sub 2}, and CrMn dimers

    SciTech Connect (OSTI)

    Desmarais, N. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Reuse, F. A. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Khanna, S. N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    2000-04-01T23:59:59.000Z

    Theoretical ab initio studies of neutral, cationic and anionic Cr{sub 2}, Mn{sub 2}, and CrMn dimers have been carried out to explore the progression of magnetic coupling with the number of electrons. It is shown that while Cr{sub 2} and Cr{sub 2}{sup -} have antiferromagnetically coupled atomic spins, Cr{sub 2}{sup +} has a ferromagnetic ground state closely followed by an antiferromagnetic state. On the other hand, all Mn{sub 2} dimers are ferromagnetic, irrespective of the charge. The neutral CrMn is ferrimagnetic while the charged CrMn are antiferromagnetic. In all cases, the charged dimers are found to be more stable than the neutral ones. The results are compared with available calculations and experiments and the difficulties associated with theoretical description and the experimental interpretations are discussed. (c) 2000 American Institute of Physics.

  1. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Mn-Si (red squares) and Mn-Ge distances (blue circles) d asof the number of Si or Ge nearest neighbours N c ; (c) localthree Mn atoms with different N c in a-Mn 0.094 Ge 0.906 .

  2. Cumulative Effects Guidance 2007 MnDOT Environmental

    E-Print Network [OSTI]

    Minnesota, University of

    relevant for actions requiring an environmental impact statement § Analysis for projects processed as EACumulative Effects Guidance 2007 MnDOT Environmental Stewardship & Streamlining Workshop Presented by Dave Gamble Federal Highway Administration Resource Center Environmental Technical Service Team #12

  3. Transverse acoustic actuation of Ni-Mn-Ga single crystals

    E-Print Network [OSTI]

    Simon, Jesse Matthew

    2007-01-01T23:59:59.000Z

    Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. ...

  4. PRECIPITATION-STRENGTHENED AUSTENITIC FE-MN-TI ALLOYS

    E-Print Network [OSTI]

    Chiang, K.-M.

    2010-01-01T23:59:59.000Z

    energy spectrums showing that precipitates are rich in titanium, andtitanium additions can reduce the austenitic stacking fault energyfault energy of the Fe-Mn austenite is lowered by titanium

  5. Ambi-site substitution of Mn in lanthanum germanate apatites

    SciTech Connect (OSTI)

    Kendrick, E. [Chemical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Knight, K.S. [ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX (United Kingdom); Slater, P.R., E-mail: p.r.slater@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-08-05T23:59:59.000Z

    A neutron diffraction study at 4 K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition 'La{sub 9.5}Mn{sub 0.5}(GeO{sub 4}){sub 6}O{sub 2.75}' is reported. The structure was refined in space group P6{sub 3}/m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing the O4 oxygen to move off site, which may indicate local regions of lower symmetry within the structure. In addition, the data suggested ambi-site substitution of Mn, with it being present on both the Ge site and the La site. Assuming no change in La:Mn:Ge ratio, a composition of La{sub 9.18}Mn{sub 0.28}(GeO{sub 4}){sub 5.8}(MnO{sub 4}){sub 0.2}O{sub 2} was determined. As such there are nominally no interstitial oxide ions, but rather cation vacancies on the La site. Therefore, the high conductivity for this sample is most likely related to the introduction of Frenkel-type defects at higher temperature, as previously proposed for other apatite-type systems containing vacancies on the La site.

  6. Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility

    E-Print Network [OSTI]

    Minnesota, University of

    Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility Coordination Process incorporates Processes There are projects where the full process is not necessary. The Mn/DOT Utilities Manual provides

  7. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    Magnetization data for a-Mn 0.15 Ge 0.85 ?lms mea- suredSi 1?x and a-Mn x Ge 1?x samples. . . . . . . . . . . . . .both a-Mn x Si 1?x and a-Mn x Ge 1?x as a func- tion of Mn

  8. Hydrothermal synthesis and catalytic properties of {alpha}- and {beta}-MnO{sub 2} nanorods

    SciTech Connect (OSTI)

    Cao, Guangsheng, E-mail: daqingcgs@163.com [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)] [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China); Su, Ling; Zhang, Xiaojuan; Li, Hui [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)] [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)

    2010-04-15T23:59:59.000Z

    One-dimensional {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} single-crystalline nanostructures were prepared by hydrothermal process. The products were characterized in detail by multiform techniques: X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Experimental results indicate that the temperature plays important roles in determining produce {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} nanorods. In addition, the as-prepared {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} nanorods showed excellent catalytic performance in the Fenton-like reaction.

  9. Workbook Contents

    U.S. Energy Information Administration (EIA) Indexed Site

    Exports to Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Noyes, MN Natural...

  10. RPT_PERIOD","R_S_NAME","LINE_NUM","PROD_CODE","PROD_NAME","PORT...

    U.S. Energy Information Administration (EIA) Indexed Site

    ",3,025,"Crude Oil",3402,"NOYES, MN","MINNESOTA",2,260,"CANADA",62,3.86,21.6,"MERCURIA ENERGY TRADING ",4966,"GREEN PORT","TX","TEXAS",3 "applicationvnd.ms-excel","MERCURIA...

  11. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    SciTech Connect (OSTI)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Kennedy, S. J.; Studer, A. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2014-05-07T23:59:59.000Z

    All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a?=?14.348?Å (space group F-43?m), 7.618?Å, and 7.158?Å (space group Fd-3?m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C}?=?38?K and T{sub C}?=?148?K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1}?=?20?K and T{sub 2}?=?49?K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

  12. Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer

    SciTech Connect (OSTI)

    Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn; Han, X. F., E-mail: xfhan@iphy.ac.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Y. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France)

    2014-04-07T23:59:59.000Z

    We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ to 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.

  13. Unique light-induced degradation in yellow-emitting K?SiF?:Mn²? phosphor

    SciTech Connect (OSTI)

    Oyama, Takuya; Adachi, Sadao, E-mail: adachi@el.gunma-u.ac.jp [Division of Electronics and Informatics, Faculty of Science and Technology, Gunma University, Kiryu-shi, Gunma 376-8515 (Japan)

    2014-10-07T23:59:59.000Z

    Photo-induced luminescence intensity degradation in yellow-emitting K?SiF?:Mn²? phosphor is studied using x-ray diffraction measurement, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, PL decay analysis, and electron spin resonance (ESR) measurement. The yellow-emitting K?SiF?:Mn²? phosphor exhibits remarkable degradation in the PL intensity under Xe lamp exposure. Coherent laser irradiation also induces degradation and its degree is in the order of He–Cd (? = 325 nm) > Ar? (488 nm) > He–Ne laser (632.8 nm). The degradation mechanism is proposed to be due to change in the valence state of manganese ions from Mn²? to Mn³? by the photooxidation (Mn²? ? Mn³?) or disproportionation reaction (2Mn²? ? Mn? + Mn³?). The ESR measurement confirms the decreased Mn²? spin density in the sample exposed with Xe lamp. The PLE spectrum suggests that the excitation of Mn³? ions occurs through energy transfer upon absorption of exciting radiation by the Mn²? ions. Thermal annealing of the degraded samples at ?200 °C causes a blueshift in the PL emission band with an appearance of the Mn??-related sharp red emission lines.

  14. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOE Patents [OSTI]

    Brager, Howard R. (Richland, WA); Garner, Francis A. (Richland, WA)

    1987-01-01T23:59:59.000Z

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  15. HgMn Stars as apparent X-ray emitters

    E-Print Network [OSTI]

    Hubrig, S; Mathys, G

    1998-01-01T23:59:59.000Z

    In the ROSAT all-sky survey 11 HgMn stars were detected as soft X-ray emitters (Berghoefer, Schmitt & Cassinelli 1996). Prior to ROSAT, X-ray observations with the Einstein Observatory had suggested that stars in the spectral range B5-A7 are devoid of X-ray emission. Since there is no X-ray emitting mechanism available for these stars (also not for HgMn stars), the usual argument in the case of an X-ray detected star of this spectral type is the existence of an unseen low-mass companion which is responsible for the X-ray emission. The purpose of the present work is to use all available data for our sample of X-ray detected HgMn stars and conclude on the nature of possible companions.

  16. Resonant spin tunneling in randomly oriented nanospheres of Mn?? acetate

    SciTech Connect (OSTI)

    Lendinez, S. [Univ. de Barcelona, Barcelona, Spain (Europe); Billinge, S. J. L. [Columbia Univ., New York, NY (United States); Zarzuela, R. [Univ. de Barcelona, Barcelona, Spain (Europe); Tejada, J. [Univ. de Barcelona, Barcelona, Spain (Europe); Terban, M. W. [Columbia Univ., New York, NY (United States); Espin, J. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Imaz, I. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Maspoch, D. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Chudnovsky, E. M. [City Univ. of New York, Bronx, NY (United States)

    2015-01-01T23:59:59.000Z

    We report measurements and theoretical analysis of resonant spin tunneling in randomly oriented nanospheres of a molecular magnet. Amorphous nanospheres of Mn?? acetate have been fabricated and characterized by chemical, infrared, TEM, X-ray, and magnetic methods. Magnetic measurements have revealed sharp tunneling peaks in the field derivative of the magnetization that occur at the typical resonant field values for the Mn?? acetate crystal in the field parallel to the easy axis.Theoretical analysis is provided that explains these observations. We argue that resonant spin tunneling in a molecular magnet can be established in a powder sample, without the need for a single crystal and without aligning the easy magnetization axes of the molecules. This is confirmed by re-analyzing the old data on a powdered sample of non-oriented micron-size crystals of Mn?? acetate. Our findings can greatly simplify the selection of candidates for quantum spin tunneling among newly synthesized molecular magnets.

  17. Assessment of the Diffusive Gradients in Thin-films (DGT) technique to assess the plant availability of Mn in soils.

    E-Print Network [OSTI]

    Mundus, Simon; Husted, Søren; Lombi, Enzo

    2009-01-01T23:59:59.000Z

    predicts copper availability to plants. EnvironmentalAttempts to assess Mn availability have been impeded due towill influence the Mn availability. Often flooding of soils

  18. The Use of Silica Coated MnO Nanoparticles to Control MRI Relaxivity in Response to Specific Physiological Changes

    E-Print Network [OSTI]

    Krishnan, Kannan M.

    -tracing could be observed due to the released Mn2þ . Intravenous infusion of MnO@SiO2 particles showed little

  19. Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

    E-Print Network [OSTI]

    Chen, Jiajun

    2010-01-01T23:59:59.000Z

    of nanosized LiMnPO 4 by combustion synthesis Figure 2. X-a) nanometric LiMnPO 4 made by combustion synthesis and b)typically formed by combustion synthesis. The average

  20. Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

    E-Print Network [OSTI]

    Chen, Jiajun

    2008-01-01T23:59:59.000Z

    of nanosized LiMnPO 4 by combustion synthesis Figure 2. X-a) nanometric LiMnPO 4 made by combustion synthesis and b)typically formed by combustion synthesis. The average

  1. Electrodeposited Al-Mn Alloys with Microcrystalline, Nanocrystalline, Amorphous and Nano-quasicrystalline Structures

    E-Print Network [OSTI]

    Ruan, Shiyun

    Al–Mn alloys with Mn content ranging from 0 to 15.8 at.% are prepared by electrodeposition from an ionic liquid at room temperature, and exhibit a remarkably broad range of structures. The alloys are characterized through ...

  2. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    E-Print Network [OSTI]

    Guchhait, S.

    2011-01-01T23:59:59.000Z

    segregation in Mn-doped Ge”, Journal of Applied Physics 101,Room-temperature ferromagnetism in Ge 1-x Mn x nanowires”,BC high-?/metal gate Ge/C alloy pMOSFETs fabricated directly

  3. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Mn)As: A new diluted magnetic semiconductor based on GaAs.Mn x Ge 1-x diluted magnetic semiconductor: experiment andx Si 1-x amorphous magnetic semiconductor. Phys. Rev. B 67 ,

  4. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    E-Print Network [OSTI]

    Guchhait, S.

    2011-01-01T23:59:59.000Z

    group-IV-based dilute magnetic semiconductors by electronicMn x Ge 1-x dilute magnetic semiconductor”, Applied Physicsamorphous Ge 1-x Mn x magnetic semiconductor films”, Journal

  5. Mn12-acetate thin film patterns and their interaction with superconductors

    E-Print Network [OSTI]

    Kim, Kyongwan

    2009-05-15T23:59:59.000Z

    Mn12-acetate single-molecule magnets (SMMs) are nano-scale magnets showing a strong magnetic anisotropy, slow relaxation and stepwise magnetic hysteresis curves. Possible applications of Mn12-acetate, e.g. for ultra high density magnetic information...

  6. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Li, A. P. et al. Magnetism in Mn x Ge 1-x semiconductorsElectronic Structure and Magnetism for Mn in Amorphous Sistructure that determines magnetism. Figure 3 shows XAS data

  7. On deformation twinning in a 17.5%Mn-TWIP steel: A physically...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    On deformation twinning in a 17.5%Mn-TWIP steel: A physically-based phenomenological model. On deformation twinning in a 17.5%Mn-TWIP steel: A physically-based phenomenological...

  8. Ba and Ni speciation in a nodule of binary Mn oxide phase composition from Lake Baikal

    E-Print Network [OSTI]

    , and absorption spectroscopy. Fe is speciated as goethite, and Mn as romanechite (psilomelane) and 10 A is separated from the other type by goethite. The binary Mn oxide banding pattern is interpreted by a two

  9. Low-temperature magnetization of (Ga,Mn) As semiconductors

    E-Print Network [OSTI]

    Jungwirth, T.; Masek, J.; Wang, KY; Edmonds, KW; Sawicki, M.; Polini, M.; Sinova, Jairo; MacDonald, AH; Campion, RP; Zhao, LX; Farley, NRS; Johal, TK; van der Laan, G.; Foxon, CT; Gallagher, BL.

    2006-01-01T23:59:59.000Z

    temperature magnetometry and XMCD experiments. A series of #1;Ga,Mn#2;As films with Mn content varying between 1.7?6.7 % in the SQUID experiments and between 2.2 and 8.4 % in the XMCD experiments were grown by low-temperature molecular beam epitaxy #1;MBE.... Magnetometry The magnetic moment of the samples is measured in a SQUID magnetometer, at 5 K and under a 0.3 T external magnetic field. The external field is necessary to overcome in-plane anisotropy fields, so that the magnetization is aligned...

  10. Electron Band Structure of MnGaN Dimiter Alexandrov1

    E-Print Network [OSTI]

    Dietz, Nikolaus

    to this orbital to be occupied. LCAO electron band structure of wurtzite MnxGa1-xN for points c1 and v15 ( = 1 of the wurtzite MnxGa1-xN are determined as well. INTRODUCTION The MnxGa1-xN semiconductor alloy is important model the MnGaN alloy on Mn content. Segregated Mn species in wurtzite GaN containing Mn

  11. Heat treatment effects on microstructure and magnetic properties of MnZn ferrite powders

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Heat treatment effects on microstructure and magnetic properties of Mn­Zn ferrite powders Ping Hu Available online 6 September 2009 Keywords: Mn­Zn ferrite Heat treatment Microstructure Magnetic property a b s t r a c t Mn­Zn ferrite powders (Mn0.5Zn0.5Fe2O4) were prepared by the nitrate­citrate auto

  12. Disentangling the Mn moments on different sublattices in the half-metallic ferrimagnet Mn3?xCoxGa

    SciTech Connect (OSTI)

    Klaer, P.; Jenkins, C.A.; Alijani, V.; Winterlik, J.; Balke, B.; Felser, C.; Elmers, H.J.

    2011-05-03T23:59:59.000Z

    Ferrimagnetic Mn{sub 3-x}Co{sub x}Ga compounds have been investigated by magnetic circular dichroism in x-ray absorption (XMCD). Compounds with x > 0.5 crystallize in the CuHg{sub 2}Ti structure. A tetragonal distortion of the cubic structure occurs for x {le} 0.5. For the cubic phase, magnetometry reveals a linearly increasing magnetization of 2x Bohr magnetons per formula unit obeying the generalized Slater-Pauling rule. XMCD confirms the ferrimagnetic character with Mn atoms occupying two different sublattices with antiparallel spin orientation and different degrees of spin localization and identifies the region 0.6 < x {le} 0.8 as most promising for a high spin polarization at the Fermi level. Individual Mn moments on inequivalent sites are compared to theoretical predictions.

  13. Exchange interaction in hexagonal MnRhP from first-principles studies

    SciTech Connect (OSTI)

    Liu, X. B., E-mail: liuxubo@uta.edu; Zhang, Qiming; Ping Liu, J., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yue, M. [College of Material Science and Engineering, Beijing University of Technology, 100022 Beijing (China); Altounian, Z. [Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada)

    2014-05-07T23:59:59.000Z

    Electronic structure and magnetic properties for MnRhP have been studied from a first-principles density functional calculation. The calculated lattice constants, a?=?6.228 Å and c?=?3.571?Å, are in good agreement with the experimental values of a?=?6.223 Å and c?=?3.585?Å. The calculated moment of Mn is 3.1 ?{sub B}/atom, resulting in a total moment of 3.0 ?{sub B}/atom due to small moments induced at Rh and P sites. The magnetic moment of Mn decreases with unit cell size. The exchange interactions are dominated by positive Mn-Mn exchange coupling (J{sub Mn?Mn}), implying a stable ferromagnetic ordering in Mn sublattice. In particular, J{sub Mn?Mn} shows a maximum value (1.5 mRy) at the the optimized unit cell size. The structural distortion or unit cell size change will affect J{sub Mn?Mn}, which is intimately related to the magneto-elastic and magneto-caloric effect.

  14. On the role of Mn(IV) vacancies in the photoreductive dissolution of hexagonal birnessite

    SciTech Connect (OSTI)

    Kwon, K.D.; Refson, K.; Sposito, G.

    2009-06-01T23:59:59.000Z

    Photoreductive dissolution of layer type Mn(IV) oxides (birnessite) under sunlight illumination to form soluble Mn(II) has been observed in both field and laboratory settings, leading to a consensus that this process is a key driver of the biogeochemical cycling of Mn in the euphotic zones of marine and freshwater ecosystems. However, the underlying mechanisms for the process remain unknown, although they have been linked to the semiconducting characteristics of hexagonal birnessite, the ubiquitous Mn(IV) oxide produced mainly by bacterial oxidation of soluble Mn(II). One of the universal properties of this biogenic mineral is the presence of Mn(IV) vacancies, long-identified as strong adsorption sites for metal cations. In this paper, the possible role of Mn vacancies in photoreductive dissolution is investigated theoretically using quantum mechanical calculations based on spin-polarized density functional theory (DFT). Our DFT study demonstrates unequivocally that Mn vacancies significantly reduce the band-gap energy for hexagonal birnessite relative to a hypothetical vacancy-free MnO{sub 2} and thus would increase the concentration of photo-induced electrons available for Mn(IV) reduction upon illumination of the mineral by sunlight. Calculations of the charge distribution in the presence of vacancies, although not fully conclusive, show a clear separation of photo-induced electrons and holes, implying a slow recombination of these charge-carriers that facilitates the two-electron reduction of Mn(IV) to Mn(II).

  15. NICKEL-FREE Fe-12Mn-0.2Ti ALLOY STEEL FOR CRYOGENIC APPLICATIONS

    E-Print Network [OSTI]

    Hwang, S.

    2010-01-01T23:59:59.000Z

    3, 1976 LBL-5401 l NICKEL-FREE Fe-12Mn-O. 2Ti ALLOY STEELowned rights. I v LBL-540l NICKEL-FREE Fe-12Mn-0.2Ti ALLOY94720 USA ABSTRACT A nickel-free Fe-12Mn-0.2Ti alloy steel

  16. Spark plasma sintering of Mn-Al-C hard magnets , E Fazakas2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Spark plasma sintering of Mn-Al-C hard magnets A Pasko1 , M LoBue1 , E Fazakas2 , L K Varga2 and F characterization of isotropic Mn-Al-C bulk samples obtained by spark plasma sintering (SPS) is reported by spark plasma sintering (SPS). This technique, to our knowledge, has not been used for preparation of Mn

  17. Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL)

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL) 4 Semester Program of Study Fall Design of Healthcare Delivery Systems ­ Lab (required) 1 (1 clinical lab) 611 Program Planning and Eval, Outcomes, & QI (required) 3 (3 lec) 510 Program Planning and Eval, Outcomes, & QI - Lab (required) 1 (1

  18. Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL)

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    , & QI (required) 3 (3 lec) 510 Program Planning and Eval, Outcomes, & QI - Lab (required) 1 (1 clinicalMasters of Nursing (MN) Degree Clinical Nurse Leader (CNL) 6 Semester Program of Study Fall Systems - Lab (required) 1 (1 clinical lab) 613 Finance and Budget (required) 2 6 (required) 612 Ethics

  19. Growing the renewable chemicals and advanced biofuels cluster in MN

    E-Print Network [OSTI]

    Levinson, David M.

    Growing the renewable chemicals and advanced biofuels cluster in MN #12;Renewable Chemical Value% Reduction 60% Reduction 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Gasoline Corn Ethanol Advanced Biofuel Cellulosic Biofuel Corn Ethanol 20% GHG Reduction Compared to gasoline: Advanced Biofuel 50% GHG Reduction e

  20. 1 Copyright 2006 by ASME Proceedings of MN2006

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    1 Copyright © 2006 by ASME Proceedings of MN2006 Multifunctional Nanocomposites 2006 September 20 of nanoparticles (including nanofibers and functional nanocomposites) in common fluids, have a potential to meet-physical characteristics. Development of new-hybrid, drag-reducing nanofluids may lead to enhanced flow and heat transfer

  1. Mn/DOT's Ombudsman Program Collaboration and Process

    E-Print Network [OSTI]

    Minnesota, University of

    Mn/DOT's Ombudsman Program Collaboration and Process #12;Overview Ombudsman exists to rebuild trust on the environmental and municipal consent processes can be critical #12;A Large Organization #12;Tragedy;Ombudsman Does Not... ·! Advocate for one party or point of view ·! Own any formal process or policy

  2. 0 1 2 3 4 5 Fig. S1. Core photograph combined with Ca, Mn, Fe counts and Mn/Fe ratio determined by XRF core

    E-Print Network [OSTI]

    Gilli, Adrian

    1. Core photograph combined with Ca, Mn, Fe counts and Mn/Fe ratio determined by XRF core scanning determined by XRF core scanning on core ZH10-19 from Lake Zurich recovered in 135 m water depth (2 m above counts and Mn/Fe ratio determined by XRF core scanning on core ZH10-21 from Lake Zurich recovered in 123

  3. Temperature dependence of the on-resonance portion Mn-NMR spectrum of a Mn(IV,IV) dimer

    E-Print Network [OSTI]

    --the tightly coupled techniques of cutting-edge cryogenic NMR experiments and highly electron correlated of leading-edge cryogenic nuclear magnetic resonance (NMR) measurements and advanced electronic structure with experimentally measureable parameters such as electric field gradient (EFG) tensor, electron's g-factor, 55 Mn

  4. The Mn effect on magnetic structure of FeMn-B amorphous metals , D.M.C. Nicholson2

    E-Print Network [OSTI]

    Widom, Michael

    magnetization and high permeability, which make them a good candidate for magnetic core materials in transformers and electrical motors. Lately, high Mn content, Fe-based bulk amorphous metals have been movement during the quenching process is determined by molecular dynamics simulation using the Vienna Ab

  5. Electronic structure and magnetism of Mn{sub 12}O{sub 12} clusters

    SciTech Connect (OSTI)

    Pederson, M.R. [Complex Systems Theory Branch-6692, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Complex Systems Theory Branch-6692, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States); Khanna, S.N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    1999-01-01T23:59:59.000Z

    To address the ferrimagnetic state of the Mn{sub 12} acetate matrix [Mn{sub 12}O{sub 12}(CH{sub 3}COO){sub 16}(H{sub 2}O){sub 4}] we have performed all-electron gradient-corrected density-functional calculations on (MnO){sub n} with n=1, 2, 4, and 12. In contrast to bulk MnO which is antiferromagnetic, the small (MnO){sub n} (n=1, 2, and 4) clusters are ferromagnetic with Mn moments of 5.0{mu}{sub B} but the ground state of Mn{sub 12}O{sub 12} is ferrimagnetic with a total magnetic moment of 20.0{mu}{sub B} as observed experimentally. The inner Mn sites in Mn{sub 12}O{sub 12} are found to have localized moments of 4.1{mu}{sub B} which are antiferromagnetically coupled to two types of outer Mn with moments of 4.2{mu}{sub B}. The cluster is shown to be marked by ionic as well as covalent bonds between Mn d and O p electrons and a strong intracluster magnetic coupling. {copyright} {ital 1999} {ital The American Physical Society}

  6. Giant Magnetic Moments and Magnetic Bistability of Stoichiomatric MnO Clusters

    SciTech Connect (OSTI)

    Nayak, S.K.; Jena, P. [Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    1998-10-01T23:59:59.000Z

    {ital Abthinspthinspinitio} calculations based on density functional theory and generalized gradient approximation reveal many unusual features of stoichiometric (MnO){sub x} (x{le}9) clusters that contrast with their bulk behavior. The clusters are ferromagnetic and carry atomiclike magnetic moments ranging from 4{mu}{sub B} to 5{mu}{sub B} per MnO unit, and the moments are localized at the Mn sites. The (MnO){sub 8} cluster, in particular, exhibits nearly degenerate ferromagnetic and atypical antiferromagnetic solutions with the ferromagnetic structure carrying a moment of 40{mu}{sub B} . The structures of (MnO){sub x} clusters are also unique with cubic and hexagonal forms competing for stability. (MnO){sub 2} and (MnO){sub 3} are unusually stable and form the foundation for further growth. {copyright} {ital 1998} {ital The American Physical Society}

  7. Bending properties of epoxy resin matrix composites filled with NiMnGa ferromagnetic shape memory alloy powders

    E-Print Network [OSTI]

    Zheng, Yufeng

    Bending properties of epoxy resin matrix composites filled with Ni­Mn­Ga ferromagnetic shape memory­Mn­Ga Composite materials Mechanical properties Microstructure Two types of epoxy resin matrix composites filled­Mn­Ga epoxy resin composites were reported, yet the bending property of Ni­Mn­Ga-polymer smart composites has

  8. Atomic-resolution study of Mn tetramer clusters using scanning tunneling Rong Yang, Haiqiang Yang, and Arthur R. Smitha

    E-Print Network [OSTI]

    Atomic-resolution study of Mn tetramer clusters using scanning tunneling microscopy Rong Yang clusters is investigated. The clusters are composed of a quadrant array of Mn atoms forming a tetramer of manganese nitride, on which are stabilized peri- odic, self-organized array of MnN-bonded Mn tetramer clus

  9. Magnetic field-induced phase transformation and variant reorientation in Ni2MnGa and NiMnCoIn magnetic shape memory alloys

    E-Print Network [OSTI]

    Karaca, Haluk Ersin

    2009-05-15T23:59:59.000Z

    The purpose of this work is to reveal the governing mechanisms responsible for the magnetic field-induced i) martensite reorientation in Ni2MnGa single crystals, ii) stress-assisted phase transformation in Ni2MnGa single crystals and iii) phase...

  10. Ferromagnetic Mn moments at SrRuO3/SrMnO3 interfaces Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439

    E-Print Network [OSTI]

    Haskel, Daniel

    Ferromagnetic Mn moments at SrRuO3/SrMnO3 interfaces Y. Choia Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 Y. Z. Yoo, O. Chmaissem, A. Ullah, S. Kolesnik, and C. W University, DeKalb, Illinois 60115 D. Haskel Advanced Photon Source, Argonne National Laboratory, Argonne

  11. Charge transport properties of CdMnTe radiation detectors

    SciTech Connect (OSTI)

    Kim K.; Rafiel, R.; Boardman, M.; Reinhard, I.; Sarbutt, A.; Watt, G.; Watt, C.; Uxa, S.; Prokopovich, D.A.; Belas, E.; Bolotnikov, A.E.; James, R.B.

    2012-04-11T23:59:59.000Z

    Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading chargecollection is reduced with increasing values of bias voltage. The electron transit time was determined from time of flight measurements. From the dependence of drift velocity on applied electric field the electron mobility was found to be n = (718 55) cm2/Vs at room temperature.

  12. Large exchange bias enhancement in (Pt(or Pd)/Co)/IrMn/Co trilayers with ultrathin IrMn thanks to interfacial Cu dusting

    SciTech Connect (OSTI)

    Vinai, G. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France); Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Moritz, J. [Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine, Bd des Aiguillettes, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Bandiera, S. [Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Prejbeanu, I. L.; Dieny, B. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France)

    2014-04-21T23:59:59.000Z

    The magnitude of exchange bias (H{sub ex}) at room temperature can be significantly enhanced in IrMn/Co and (Pt(or Pd)/Co)/IrMn/Co structures thanks to the insertion of an ultrathin Cu dusting layer at the IrMn/Co interface. The combination of trilayer structure and interfacial Cu dusting leads to a three-fold increase in H{sub ex} as compared to the conventional IrMn/Co bilayer structure, with an increased blocking temperature (T{sub B}) and a concave curvature of the temperature dependence H{sub ex}(T), ideal for improved Thermally Assisted-Magnetic Random Access Memory storage layer. This exchange bias enhancement is ascribed to a reduction of the spin frustration at the IrMn/Co interface thanks to interfacial Cu addition.

  13. Ge{sub 1-x}Mn{sub x} heteroepitaxial quantum dots: Growth, morphology, and magnetism

    SciTech Connect (OSTI)

    Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

    2013-02-21T23:59:59.000Z

    Heteroepitaxial Ge{sub 1-x}Mn{sub x} quantum dots (QDs) were grown on Si (001) by molecular beam epitaxial co-deposition, with x = 0 to 0.10, in order to explore the interaction between Mn content, surface morphological evolution, and magnetism. Morphological evolution typical of the Ge/Si (001) system was observed, where the effect of Mn on surface morphology is surprisingly minimal at low Mn content, with no obvious surface morphological indicators of second phase formation. As the Mn content increases, secondary phase formation becomes evident, appearing to heterogeneously nucleate on or within Ge QDs. Still higher Mn concentrations lead to extensive second phase formation interspersed with an array of Ge QDs. Although ferromagnetism up to 220 K is observed, likely arising from intermetallic precipitates, there is no clear evidence for room-temperature ferromagnetism associated with a dilute magnetic solution phase.

  14. Time resolved magneto-optical studies of ferromagnetic InMnSb films

    SciTech Connect (OSTI)

    Frazier, M.; Kini, R. N.; Nontapot, K.; Khodaparast, G. A. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences 02-668 Warsaw (Poland); Liu, X.; Furdyna, J. K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2008-02-11T23:59:59.000Z

    We report time resolved magneto-optical measurements in InMnSb ferromagnetic films with 2% and 2.8% Mn contents grown by low temperature molecular beam epitaxy. In order to probe a possible interaction between the spins of photoexcited carriers and the Mn ions, we measured spin dynamics before and after aligning the Mn ions by applying an external magnetic field at temperatures above and below the samples' Curie temperatures. We observed no significant temperature or magnetic field dependence in the relaxation times and attribute the observed dynamics entirely to the relaxation of photoexcited electrons in the conduction band where the s-d coupling with the localized Mn ions is significantly weaker compared to the p-d exchange coupling. We observed several differences in the optical response of our InMnSb samples which could have been influenced mainly by the samples' growth conditions.

  15. IV. -PHOTOMAGNETISM AND CONDUCT I W r PHOTOMAGNETIC EFFECT IN A Li-Mn FERRITE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    IV. - PHOTOMAGNETISM AND CONDUCT I W r PHOTOMAGNETIC EFFECT IN A Li-Mn FERRITE P. BERNSTEIN and T'effet photomagnCtique dans le ferrite Fez,I oLi0.45Mn0.4504 au moyen de la variation de la perm investigated in a Fez.loLi0.45Mn0.4504ferrite by looking at the variations of the permeability under light

  16. Doping-level-dependent optical properties of GaN:Mn O. Gelhausen,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    for system response. The optical absorption spectra recorded at 2 K of nomi- nally undoped GaN, GaN:Mn, and GaN:Mn:Si are presented in Fig. 1. An absorption band with a zero phonon line ZPL at 1.414 0.002 eDoping-level-dependent optical properties of GaN:Mn O. Gelhausen,a) E. Malguth, and M. R. Phillips

  17. Optical Properties of Mn-doped GaN O. Gelhausen1

    E-Print Network [OSTI]

    Nabben, Reinhard

    measurements. In the GaN:Mn, an intense absorption peak at 1.414 +/- 0.002 eV was observed. This peakOptical Properties of Mn-doped GaN O. Gelhausen1 , E. Malguth1,3 , M. R. Phillips1 , E. M. Goldys2, Germany ABSTRACT Molecular beam epitaxy-grown GaN with different Mn concentrations (5-23 x 1019 cm-3

  18. Strain mediated coupling in magnetron sputtered multiferroic PZT/Ni-Mn-In/Si thin film heterostructure

    SciTech Connect (OSTI)

    Singh, Kirandeep; Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand (India); Singh, Sushil Kumar [Functional Materials Division, Solid State Physics Lab (SSPL), DRDO, Lucknow Road, Timarpur, Delhi 110054 (India)

    2014-09-21T23:59:59.000Z

    The strain mediated electrical and magnetic properties were investigated in PZT/Ni-Mn-In heterostructure deposited on Si (100) by dc/rf magnetron sputtering. X-ray diffraction pattern revealed that (220) orientation of Ni-Mn-In facilitate the (110) oriented tertragonal phase growth of PZT layer in PZT/Ni-Mn-In heterostructure. A distinctive peak in dielectric constant versus temperature plots around martensitic phase transformation temperature of Ni-Mn-In showed a strain mediated coupling between Ni-Mn-In and PZT layers. The ferroelectric measurement taken at different temperatures exhibits a well saturated and temperature dependent P-E loops with a highest value of P{sub sat}???55 ?C/cm{sup 2} obtained during martensite-austenite transition temperature region of Ni-Mn-In. The stress induced by Ni-Mn-In layer on upper PZT film due to structural transformation from martensite to austenite resulted in temperature modulated Tunability of PZT/Ni-Mn-In heterostructure. A tunability of 42% was achieved at 290?K (structural transition region of Ni-Mn-In) in these heterostructures. I-V measurements taken at different temperatures indicated that ohmic conduction was the main conduction mechanism over a large electric field range in these heterostructures. Magnetic measurement revealed that heterostructure was ferromagnetic at room temperature with a saturation magnetization of ?123?emu/cm{sup 3}. Such multiferroic heterostructures exhibits promising applications in various microelectromechanical systems.

  19. Mn(II) Oxidation by an Ascomycete Fungus is Linked to Superoxide...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Asexual Reproduction. Abstract: Manganese (Mn) oxides are among the most reactive minerals within the environment, where they control the bioavailability of carbon, nutrients,...

  20. Enhancing SMM properties via axial distortion of Mn-3(III) clusters 

    E-Print Network [OSTI]

    Parsons S.; Brechin, E.K.; Collins A.; Karotsis G.; Jones L.F.; Inglis R.; Wernsdorfer W.; Perlepes S.P.

    2008-01-01T23:59:59.000Z

    Replacement of carboxylate and solvent with facially capping tripodal ligands enhances the single-molecule magnet (SMM) properties of [Mn-3(III)] triangles.

  1. Metastable phase boundaries of quasicrystalline phases. [Al-Mn; Al-Ru

    SciTech Connect (OSTI)

    Follstaedt, D.M.; Knapp, J.A.

    1987-01-01T23:59:59.000Z

    The melting curve (T/sub 0/) of the metastable icosahedral phase and the liquidus of the decagonal phase of Al-Mn have been obtained for 14 to 22 at. % Mn. Icosahedral Al-Mn has a congruent melting point of 910 +- 20/sup 0/C at 20 at. % Mn, and melts approx.30/sup 0/C lower than crystalline compounds with the same composition. Icosahedral Al/sub 82/Ru/sub 18/ was determined to melt at 1260 +- 30/sup 0/C. These results were obtained by forming single-phase icosahedral alloys with ion beam mixing, and by rapid heating to accurately known temperatures with electron beams.

  2. HIGH RESOLUTION SCANNING AUGER MICROSCOPIC INVESTIGATION OF INTERGRANULAR FRACTURE IN AS-QUENCHED Fe-12Mn

    E-Print Network [OSTI]

    Lee, H.J.

    2013-01-01T23:59:59.000Z

    contents in Fe-Mn alloys. Scanning electron fractographsTransactions HIGH RESOLUTION SCANNING AUGER MICROSCOPICof Califomia. HIGH RESOLUTION SCANNING AUGER MICROSCOPIC

  3. Preparation and electrochemical properties of lamellar MnO{sub 2} for supercapacitors

    SciTech Connect (OSTI)

    Yan, Jun; Wei, Tong [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Cheng, Jie [Research Institute of Chemical Defense, Beijing 100083 (China)] [Research Institute of Chemical Defense, Beijing 100083 (China); Fan, Zhuangjun, E-mail: fanzhj666@163.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2010-02-15T23:59:59.000Z

    Lamellar birnessite-type MnO{sub 2} materials were prepared by changing the pH of the initial reaction system via hydrothermal synthesis. The interlayer spacing of MnO{sub 2} with a layered structure increased gradually when the initial pH value varied from 12.43 to 2.81, while the MnO{sub 2}, composed of {alpha}-MnO{sub 2} and {gamma}-MnO{sub 2}, had a rod-like structure at pH 0.63. Electrochemical studies indicated that the specific capacitance of birnessite-type MnO{sub 2} was much higher than that of rod-like MnO{sub 2} at high discharge current densities due to the lamellar structure with fast intercalation/deintercalation of protons and high utilization of MnO{sub 2}. The initial specific capacitance of MnO{sub 2} prepared at pH 2.81 was 242.1 F g{sup -1} at 2 mA cm{sup -2} in 2 mol L{sup -1} (NH{sub 4}){sub 2}SO{sub 4} aqueous electrolyte. The capacitance increased by about 8.1% of initial capacitance after 200 cycles at a current density of 100 mA cm{sup -2}.

  4. Protective effects of ebselen (Ebs) and para-aminosalicylic acid (PAS) against manganese (Mn)-induced neurotoxicity

    SciTech Connect (OSTI)

    Marreilha dos Santos, A.P., E-mail: apsantos@ff.ul.pt [I-Med.UL, Department of Toxicology and Food Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon (Portugal); Lucas, Rui L.; Andrade, Vanda; Mateus, M. Luísa [I-Med.UL, Department of Toxicology and Food Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon (Portugal)] [I-Med.UL, Department of Toxicology and Food Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon (Portugal); Milatovic, Dejan; Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232 (United States)] [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Batoreu, M. Camila [I-Med.UL, Department of Toxicology and Food Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon (Portugal)] [I-Med.UL, Department of Toxicology and Food Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon (Portugal)

    2012-02-01T23:59:59.000Z

    Chronic, excessive exposure to manganese (Mn) may induce neurotoxicity and cause an irreversible brain disease, referred to as manganism. Efficacious therapies for the treatment of Mn are lacking, mandating the development of new interventions. The purpose of the present study was to investigate the efficacy of ebselen (Ebs) and para-aminosalicylic acid (PAS) in attenuating the neurotoxic effects of Mn in an in vivo rat model. Exposure biomarkers, inflammatory and oxidative stress biomarkers, as well as behavioral parameters were evaluated. Co-treatment with Mn plus Ebs or Mn plus PAS caused a significant decrease in blood and brain Mn concentrations (compared to rats treated with Mn alone), concomitant with reduced brain E{sub 2} prostaglandin (PGE{sub 2}) and enhanced brain glutathione (GSH) levels, decreased serum prolactin (PRL) levels, and increased ambulation and rearing activities. Taken together, these results establish that both PAS and Ebs are efficacious in reducing Mn body burden, neuroinflammation, oxidative stress and locomotor activity impairments in a rat model of Mn-induced toxicity. -- Highlights: ? The manuscript is unique in its approach to the neurotoxicity of Mn. ? The manuscript incorporates molecular, cellular and functional (behavioral) analyses. ? Both PAS and Ebs are effective in restoring Mn behavioral function. ? Both PAS and Ebs are effective in reducing Mn-induced oxidative stress. ? Both PAS and Ebs led to a decrease in Mn-induced neuro-inflammation.

  5. Opti-MN Impact House Presentation | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed offOCHCO2:Introduction toManagementOPAM PolicyOfEnergy Online1 MarchOpti-MN Impact House

  6. MN Office of Energy Security | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to: navigation, searchOfRose Bend < MHKconverter <WAG BuoyYOG < MHKbioWaveTHETugboat/MN

  7. DOE - Office of Legacy Management -- Elk River Reactor - MN 01

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTable ofArizonaBuffalo -Elk River Reactor - MN 01 FUSRAP

  8. Lattice Mn3+ Behaviors in Li4Ti5O12/LiNi0.5Mn1.5O4 Full Cells

    SciTech Connect (OSTI)

    Zheng, Jianming; Xiao, Jie; Nie, Zimin; Zhang, Jiguang

    2013-05-28T23:59:59.000Z

    High voltage spinels LiNi0.5Mn1.5O4 (LNMO) with different contents of residual Mn3+ ions have been evaluated in full cells using Li4Ti5O12 (LTO) as standard anode. Greatly improved cycling stability has been observed for all spinels in LTO-limited full cell, compared with those in LNMO-limited ones, while the underlying mechanisms are quite different. It has been discovered that the participation of active Mn3+ in the extended cycling and thus its observable contribution to Li+ diffusion kinetics depend on the limiting electrode and the sufficiency of Li+ ions. Potential Mn dissolution has also been discussed to identify the key factors that need to be considered to construct full cells employing high voltage spinel as the cathode.

  9. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    various transition or rare-earth metals provide a rich ?eldTransition Metal (Mn) and Rare Earth (Gd) Doped AmorphousTransition Metal (Mn) and Rare Earth (Gd) Doped Amorphous

  10. Photovoltaic effect in multiphase Bi-Mn-O thin J. P. Chakrabartty,1

    E-Print Network [OSTI]

    Photovoltaic effect in multiphase Bi-Mn-O thin films J. P. Chakrabartty,1 R. Nechache,2,4 C and therefore the photovoltaic conversion efficiency. Specifically, a higher Bi/Mn ratio (towards unity separation. ©2013 Optical Society of America OCIS codes: (040.5350) Photovoltaic; (160.2260) Ferroelectrics

  11. Irradiated Esophageal Cells are Protected from Radiation-Induced Recombination by MnSOD Gene Therapy

    E-Print Network [OSTI]

    Engelward, Bevin

    Irradiated Esophageal Cells are Protected from Radiation-Induced Recombination by MnSOD Gene. Irradiated Esophageal Cells are Protected from Radiation- Induced Recombination by MnSOD Gene Therapy. Radiat,a Bevin Engelward,b Michael Epperlya and Joel S. Greenbergera,1 a Departments of Radiation Oncology

  12. Magnetic cluster excitations in the antiferromagnetic phase of a-MnMoO4 

    E-Print Network [OSTI]

    Ochsenbein, Stefan T; Chaboussant, Gregory; Sieber, Andreas; Gudel, Hans U; Janssen, Stefan; Furrer, Albert; Attfield, J. Paul

    2003-01-01T23:59:59.000Z

    The tetramer-based compound a-MnMoO4 exhibits four prominent peaks in the inelastic neutron scattering (INS) spectrum between 0.5 and 2.0 meV below 10 K. They are assigned to magnetic excitations of the (Mn2+)4 rhombus ...

  13. An Analysis of Mn-Zn Ferrite Microstructure by Impedance Spectroscopy, STEM and EDS Characterisations.

    E-Print Network [OSTI]

    Boyer, Edmond

    An Analysis of Mn-Zn Ferrite Microstructure by Impedance Spectroscopy, STEM and EDS.loyau@satie.ens-cachan.fr Abstract AC resistivity measurement results on Mn-Zn sintered ferrite were analyzed in the 0.1-500 MHz of the main limitations in frequency increase is the energy dissipations by losses in ferrites that produce

  14. Synthesis and Characterization of NiMnGa Ferromagnetic Shape Memory Alloy Thin Films

    E-Print Network [OSTI]

    Jetta, Nishitha

    2011-10-21T23:59:59.000Z

    for fabricating NiMnGa thin films with desired composition and microstructure and hence unique properties for future MEMS actuator materials and characterize their properties to aid better understanding of their behavior. In this project NiMnGa thin films have...

  15. Short communication The composite rods of MnO and multi-walled carbon nanotubes as

    E-Print Network [OSTI]

    Ceder, Gerbrand

    Short communication The composite rods of MnO and multi-walled carbon nanotubes as anode materialsO as an anode material for lithium ion batteries are significantly improved. The MnO/MWNTs composite shows a Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong

  16. Additive and Competitive Effects of Bacteria and Mn Oxides on Arsenite Oxidation Kinetics

    E-Print Network [OSTI]

    Sparks, Donald L.

    Additive and Competitive Effects of Bacteria and Mn Oxides on Arsenite Oxidation Kinetics L oxidizing As(III) at the same time than for either component alone. The additive effect of the mixed cell even though As(III) was oxidized fastest in a mixed cell--MnO2 system. The additive effect of biotic

  17. NICKEL-FREE Fe-12Mn-0.2Ti ALLOY STEEL FOR CRYOGENIC APPLICATIONS

    E-Print Network [OSTI]

    Hwang, S.

    2010-01-01T23:59:59.000Z

    Parr, J. Gordon, J. Iron and Steel Inst. B, vol. 283,137 (Properties of Fe-12Mn-0.2Ti Steel at -196°C Yield Stress (FREE Fe-12Mn-O. 2Ti ALLOY STEEL FOR CRYOGENIC APPLICATIONS

  18. austenitnoj cr-mn stali: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    cr-mn stali First Page Previous Page 1 2 3 4 5 6 Next Page Last Page Topic Index 1 Cavitation erosion of laser processed Fe-Cr-Mn and Fe-Cr-Co alloys CiteSeer Summary: Received...

  19. Single-Crystalline Diluted Magnetic Semiconductor GaN:Mn Nanowires**

    E-Print Network [OSTI]

    Yang, Peidong

    Single-Crystalline Diluted Magnetic Semiconductor GaN:Mn Nanowires** By Heon-Jin Choi*, Han-mediated ferromagnetism. These ferromagnetic GaN:Mn nanowires represent an important class of nanometer-scale building blocks for spintronics. Theoretical studies indicate that transition-metal-doped GaN possesses

  20. Core-level satellites and outer core-level multiplet splitting in Mn model compounds

    SciTech Connect (OSTI)

    Nelson, A. J. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States); Reynolds, John G. [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States); Roos, Joseph W. [Ethyl Corporation, Richmond, Virginia 23217 (United States)] [Ethyl Corporation, Richmond, Virginia 23217 (United States)

    2000-07-01T23:59:59.000Z

    We report a systematic study of the Mn 2p, 3s, and 3p core-level photoemission and satellite structures for Mn model compounds. Charge transfer from the ligand state to the 3d metal state is observed and is distinguished by prominent shake-up satellites. We also observe that the Mn 3s multiplet splitting becomes smaller as the Mn oxidation state increases, and that 3s-3d electron correlation reduces the branching ratio of the {sup 7}S:{sup 5}S states in the Mn 3s spectra. In addition, as the ligand electronegativity decreases, the spin-state purity is lost in the 3s spectra, as evidenced by peak broadening. Our results are best understood in terms of the configuration-interaction model including intrashell electron correlation, charge transfer, and final-state screening. (c) 2000 American Vacuum Society.

  1. Neutron diffraction study of MnNiGa{sub 2}—Structural and magnetic behaviour

    SciTech Connect (OSTI)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Ma, L.; Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Hofmann, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Avdeev, M.; Kennedy, S. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Md Din, M. F.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Hoelzel, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Fachbereich Materialwissenschaften, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2014-05-07T23:59:59.000Z

    MnNiGa{sub 2} crystallizes in the L21 (Heusler) structure and has a ferromagnetic ordering temperature T{sub C}???192?K. Rietveld refinement of the neutron diffraction patterns indicates that the Ga atoms occupy the equivalent 8c position, while Mn and Ni share the 4a (0, 0, 0) and 4b (0.5, 0.5, 0.5) sites with a mixed occupancy of Mn and Ni atoms. It is found that that ?83% of Mn and ?17% Ni are located at the 4a site while ?83% of Ni and ?17% Mn occupy the 4b site. There is no evidence of a magneto-volume effect around T{sub C}. In agreement with this finding, our detailed critical exponent analyses of isothermal magnetization curves and the related Arrott plots confirm that the magnetic phase transition at T{sub C} is second order.

  2. Surface alloys of icosahedral AlMnSi with phason distortions

    SciTech Connect (OSTI)

    Follstaedt, D.M.; Knapp, J.A.

    1986-12-01T23:59:59.000Z

    The microstructures produced by electron-beam melting and by ion-beam mixing Al/Mn and Al/Mn/Si layers on Si substrates are examined. The treatments were found to incorporate Si from the substrate into the surface alloy. Several phases formed, depending on treatment, including ..cap alpha..- and ..beta..-AlMnSi, ..mu..-AlMn (epitaxial on Si(111), and amorphous and icosahedral AlMnSi. The observed microstructures relate the novel icosahedral phase to other phases and elucidate its formation kinetics. Diffraction patterns from large icosahedral grains (up to 5 ..mu..m) show distortions in the position and shape of weak (but not strong) reflections, as predicted for phason defects in a quasicrystalline lattice, one of the structures proposed for icosahedral phases.

  3. Mn3O4-Graphene Hybrid as a High-Capacity Anode Material for Lithium Ion Hailiang Wang,,

    E-Print Network [OSTI]

    Cui, Yi

    Mn3O4-Graphene Hybrid as a High-Capacity Anode Material for Lithium Ion Batteries Hailiang Wang hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles

  4. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon

    SciTech Connect (OSTI)

    Prestat, E., E-mail: eric.prestat@gmail.com; Porret, C.; Favre-Nicolin, V.; Tainoff, D.; Boukhari, M.; Bayle-Guillemaud, P.; Jamet, M.; Barski, A., E-mail: andre.barski@cea.com [INAC, SP2M, CEA and Université Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2014-03-10T23:59:59.000Z

    In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots.

  5. Structural characterization of terrestrial microbial Mn oxides from Pinal Creek, AZ

    SciTech Connect (OSTI)

    Bargar, John; Fuller, Christopher; Marcus, Matthew A.; Brearley, Adrian J.; Perez De la Rosa, M.; Webb, Samuel M.; Caldwell, Wendel A.

    2008-03-19T23:59:59.000Z

    The microbial catalysis of Mn(II) oxidation is believed to be a dominant source of abundant sorption- and redox-active Mn oxides in marine, freshwater, and subsurface aquatic environments. In spite of their importance, environmental oxides of known biogenic origin have generally not been characterized in detail from a structural perspective. Hyporheic zone Mn oxide grain coatings at Pinal Creek, Arizona, a metals-contaminated stream, have been identified as being dominantly microbial in origin and are well studied from bulk chemistry and contaminant hydrology perspectives. This site thus presents an excellent opportunity to study the structures of terrestrial microbial Mn oxides in detail. XRD and EXAFS measurements performed in this study indicate that the hydrated Pinal Creek Mn oxide grain coatings are layer-type Mn oxides with dominantly hexagonal or pseudo-hexagonal layer symmetry. XRD and TEM measurements suggest the oxides to be nanoparticulate plates with average dimensions on the order of 11 nm thick x 35 nm diameter, but with individual particles exhibiting thickness as small as a single layer and sheets as wide as 500 nm. The hydrated oxides exhibit a 10-A basal-plane spacing and turbostratic disorder. EXAFS analyses suggest the oxides contain layer Mn(IV) site vacancy defects, and layer Mn(III) is inferred to be present, as deduced from Jahn-Teller distortion of the local structure. The physical geometry and structural details of the coatings suggest formation within microbial biofilms. The biogenic Mnoxides are stable with respect to transformation into thermodynamically more stable phases over a time scale of at least 5 months. The nanoparticulate layered structural motif, also observed in pure culture laboratory studies, appears to be characteristic of biogenic Mn oxides and may explain the common occurrence of this mineral habit in soils and sediments.

  6. Mn Occupations in Ga1-xMnxN Dilute Magnetic Semiconductors Probed by X-Ray Absorption Near-Edge Structure Spectroscopy

    SciTech Connect (OSTI)

    Wei Shiqiang; Yan Wensheng; Sun Zhihu; Liu Qinghua; Zhong Wenjie [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Zhang Xinyi [Department of Physics, Surface Physics Laboratory (National Key Laboratory), Fudan University, 220 Handan Road, Shanghai 200433 (China); Synchrotron Radiation Research Center, Fudan University, 220 Handan Road, Shanghai 200433 (China); Oyanagi, H. [Photonics Research Institute, National Institute of Advanced Industrial Science and Technology 1-1-1 Umezono Tsukuba, Ibaraki 305-8568 (Japan); Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

    2007-02-02T23:59:59.000Z

    X-ray absorption near-edge structure (XANES) is used to study the characteristics of different sites of Mn in the Ga1-xMnxN dilute magnetic semiconductor (DMS) with zinc-blende structure. The XANES spectra of representative Mn occupation sites (substitutional MnGa, interstitial MnI, MnGa-MnI dimer and Mn cluster) in GaN lattice are theoretically calculated and compared with experimental results. The substitutional Mn in GaN is characterized by a pre-edge peak at 2.0 eV and a post-edge multiple-scattering peak at 29.1 eV. The peaks shift in position and drop in intensity dramatically for the interstitial MnI and MnGa-MnI dimmer, and disappear completely for Mn clusters. We propose that the distinct characteristics of Mn K-edge XANES spectra for different Mn sites favor to discriminate Mn occupations in GaMnN DMS.

  7. Quantum Anomalous Hall Effect in Hg_1-yMn_yTe Quantum Wells

    SciTech Connect (OSTI)

    Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-19T23:59:59.000Z

    The quantum Hall effect is usually observed when the two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall effect, can be realized in Hg{sub 1-y}Mn{sub y}Te quantum wells, without the external magnetic field and the associated Landau levels. This effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This effect enables dissipationless charge current in spintronics devices.

  8. Melting point measurements for quasicrystalline phases. [Al-Mn; icosahedral and decagonal phases

    SciTech Connect (OSTI)

    Knapp, J.A.; Follstaedt, D.M.

    1986-01-01T23:59:59.000Z

    Melting transitions of metastable quasicrystalline phases of Al-Mn have been observed using rapid electron-beam heating of fine-grained icosahedral surface layers. The congruent melting point for icosahedral Al/sub 80/Mn/sub 20/ was directly measured to be 910 +- 20/sup 0/C. Heating to higher temperatures shows another transition which is inferred to correspond to the liquidus of the decagonal phase at 965 +- 20/sup 0/C for 20 at. % Mn. The microstructure and formation kinetics of the decagonal phase are discussed, and its electron diffraction is described.

  9. Tailoring interlayer coupling and coercivity in Co/Mn/Co trilayers by controlling the interface roughness

    SciTech Connect (OSTI)

    Zhang, Bin; Wu, Chii-Bin; Kuch, Wolfgang, E-mail: kuch@physik.fu-berlin.de [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany)

    2014-06-21T23:59:59.000Z

    Epitaxial Co/Mn/Co trilayers with a wedged Mn layer were grown on Cu(001) and studied by magneto-optical Kerr effect measurements. The bottom Co film as well as the Mn film exhibits a layer-by-layer growth mode, which allows to modify both interface roughnesses on the atomic scale by tuning the thicknesses of the films to achieve a certain filling of their topmost atomic layers. The onset of antiferromagnetic order in the Mn layer at room temperature was found at thicknesses of 4.1 (4.8) and 3.4 (4.0) atomic monolayers (ML) for a filled (half-filled) topmost atomic layer of the bottom Co film in Mn/Co bilayers and Co/Mn/Co trilayers, respectively. Magnetization loops with only one step were found for a trilayer with half-filled topmost atomic layer of the bottom Co film, while loops with two separate steps have been observed in trilayers with an integer number of atomic layers in the bottom Co film. The coercivity of the top Co film shows an oscillation with 1 ML period as a function of the Mn thickness above 10 ML, which is interpreted as the influence of the atomic-scale control of the interface roughness on the interface exchange coupling between the antiferromagnetic Mn and the top ferromagnetic (FM) Co layer. The strength of the magnetic interlayer coupling between the top and bottom Co layers through the Mn layer for an integer number of atomic layers in the bottom Co layer, deduced from minor-loop measurements, exhibits an oscillation with a period of 2 ML Mn thickness, indicative of direct exchange coupling through the antiferromagnetic Mn layer. In addition, a long-period interlayer coupling of the two FM layers with antiparallel coupling maxima at Mn thicknesses of 2.5, 8.2, and 13.7 ML is observed and attributed to indirect exchange coupling of the Rudermann-Kittel-Kasuya-Yosida type.

  10. First-principles study of spin-transfer torque in Co{sub 2}MnSi/Al/Co{sub 2}MnSi spin-valve

    SciTech Connect (OSTI)

    Tang, Ling, E-mail: lingtang@zjut.edu.cn; Yang, Zejin, E-mail: zejinyang@zjut.edu.cn [Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023 (China)

    2013-11-21T23:59:59.000Z

    The spin-transfer torque (STT) in Co{sub 2}MnSi(CMS)/Al/Co{sub 2}MnSi spin-valve system with and without interfacial disorder is studied by a first-principles noncollinear wave-function-matching method. It is shown that in the case of clean interface the angular dependence of STT for CoCo/Al (the asymmetry parameter ??4.5) is more skewed than that for MnSi/Al (??2.9), which suggests the clean CoCo/Al architecture is much more efficient for the application on radio frequency oscillation. We also find that even with interfacial disorder the spin-valve of half-metallic CMS still has a relatively large parameter ? compared to that of conventional ferromagnet. In addition, for clean interface the in-plane torkance of MnSi/Al is about twice as large as that of CoCo/Al. However, as long as the degree of interfacial disorder is sufficiently large, the CoCo/Al and MnSi/Al will show approximately the same magnitude of in-plane torkance. Furthermore, our results demonstrate that CMS/Al/CMS system has very high efficiency of STT to switch the magnetic layer of spin-valve.

  11. Robust ferroelectric state in multiferroic Mn 1 ? x Zn x WO 4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chaudhury, R. P.; Ye, F.; Fernandez-Baca, J. A.; Lorenz, B.; Wang, Y. Q.; Sun, Y. Y.; Mook, H. A.; Chu, C. W.

    2011-01-01T23:59:59.000Z

    We report on the remarkably robust ferroelectric state in the multiferroic compound Mn1-xZnxWO?. Substitution of the magnetic Mn²? with nonmagnetic Zn²? reduces the magnetic exchange and provides control of the various magnetic and multiferroic states of MnWO?. Only 5% of Zn substitution results in complete suppression of the frustrated collinear (paraelectric) low-temperature phase. The helical magnetic and ferroelectric phase develops as the ground state. The multiferroic state is stable up to a high level of substitution of more than 50%. The magnetic, thermodynamic, and dielectric properties, as well as the ferroelectric polarization of single crystals of Mn1-xZnxWO?, are studied for different substitutions up to x=0.5. The magnetic phases have been identified in single-crystal neutron-scattering experiments. The ferroelectric polarization scales with the neutron intensity of the incommensurate peak of the helical phase.

  12. Formation of nano-crystalline todorokite from biogenic Mn Xiong Han Feng a,1

    E-Print Network [OSTI]

    Sparks, Donald L.

    Formation of nano-crystalline todorokite from biogenic Mn oxides Xiong Han Feng a,1 , Mengqiang Zhu oxides in the environment. Additionally this method may be a viable biosynthesis route for porous, nano

  13. Mn solid solutions in self-assembled Ge/Si (001) quantum dot heterostructures

    SciTech Connect (OSTI)

    Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

    2012-12-10T23:59:59.000Z

    Heteroepitaxial Ge{sub 0.98}Mn{sub 0.02} quantum dots (QDs) on Si (001) were grown by molecular beam epitaxy. The standard Ge wetting layer-hut-dome-superdome sequence was observed, with no indicators of second phase formation in the surface morphology. We show that Mn forms a dilute solid solution in the Ge quantum dot layer, and a significant fraction of the Mn partitions into a sparse array of buried, Mn-enriched silicide precipitates directly underneath a fraction of the Ge superdomes. The magnetic response from the ultra-thin film indicates the absence of robust room temperature ferromagnetism, perhaps due to anomalous intermixing of Si into the Ge quantum dots.

  14. Growth of GaMnAs under near-stoichiometric conditions

    SciTech Connect (OSTI)

    Avrutin, V.; Humienik, D.; Frank, S.; Koeder, A.; Schoch, W.; Limmer, W.; Sauer, R.; Waag, A. [Abteilung Halbleiterphysik, Universitaet Ulm, D-89069 Ulm (Germany); Institut fuer Halbleitertechnik, Technische Universitaet (TU) Braunschweig, Hans-Sommer-Strasse 66, D38103 Braunschweig (Germany)

    2005-07-15T23:59:59.000Z

    We studied the effect of the V/III flux ratio and substrate temperature on magnetotransport properties and lattice parameters of Ga{sub 0.96}Mn{sub 0.04}As grown by molecular-beam epitaxy. For all the substrate temperatures, the conductivities and Curie temperatures of the layers were found to increase as the V/III flux ratio approaches 1. A Curie temperature as high as 95 K was achieved for the Ga{sub 0.96}Mn{sub 0.04}As samples grown at 240 deg. C and a V/III ratio of about 1.5. The lattice parameter of Ga{sub 0.96}Mn{sub 0.04}As increased with decreasing V/III ratio and/or increasing growth temperature. Possible reasons for the effect of the V/III ratio on the magnetotransport properties and lattice parameter of GaMnAs are discussed.

  15. Fabrication and Luminescence of ZnS:Mn2+ Nanoflowers. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of ZnS:Mn2+ nanoparticles are prepared and characterized. The configurations of these fractal structures are very sensitive to both the pH values of the particle solutions from...

  16. Synthesis and Luminescence of ZnMgS:Mn2+ Nanoparticles. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    followed by a post-annealing process, thus showing the features of less complexity, low cost, and easy incorporation of dopants. In comparison with the emission of ZnS:Mn2+...

  17. Understanding and development of combined acoustic and magnetic actuation of Ni?MnGa single crystals

    E-Print Network [OSTI]

    Techapiesancharoenkij, Ratchatee, 1979-

    2007-01-01T23:59:59.000Z

    Ni-Mn-Ga based ferromagnetic shape memory alloys (FSMAs) have emerged as a promising new class of active materials capable of producing a large (several %) magnetic-field-induced strain (MFIS). FSMAs still have several ...

  18. Characterization of LiNi?.?Mn?.?O? Thin Film Cathode Prepared by Pulsed Laser Deposition

    E-Print Network [OSTI]

    Xia, Hui

    LiNi?.?Mn?.?O? thin films have been grown by pulsed laser deposition (PLD) on stainless steel (SS) substrates. The crystallinity and structure of thin films were investigated by X-ray diffraction (XRD). Microstructure and ...

  19. Response of Citrus volkameriana (L.) plants to different Mn concentrations under hydroponic conditions.

    E-Print Network [OSTI]

    Papadakis, Ioannis; Sotiropoulos, Thomas; Giannakoula, Anastasia; Antonopoulou, Chrysovalantou; Therios, Ioannis

    2009-01-01T23:59:59.000Z

    and Mn +2 stress conditions. Plant Sci. 165, 769-776. Heuer,and glycinebetaine on growth of salt-stressed tomato plants.Plant Sci. 165, 693-699. Hoagland, D. R. , Arnon, D. I. (

  20. Frequency Response of Acoustic-Assisted Ni–Mn–Ga Ferromagnetic- Shape-Memory-Alloy Actuator

    E-Print Network [OSTI]

    Techapiesancharoenkij, Ratchatee

    A prototype of Ni–Mn–Ga based ferromagnetic-shape-memory-alloy (FSMA) actuator was designed and built; an acoustic-assist technique was applied to the actuator to enhance its performance. A piezoelectric stack actuator was ...

  1. Synthesis and characterization of MnPS{sub 3} for hydrogen sorption

    SciTech Connect (OSTI)

    Ismail, N., E-mail: nahlaismail24@yahoo.co [Physical Chemistry Department, National Research Center, Center of Excellence for Advanced Science, Renewable Energy Group, Cairo (Egypt); Temerk, Y.M. [Assiut University, Faculty of Science, Chemistry Department, Assuit (Egypt); El-Meligi, A.A. [Physical Chemistry Department, National Research Center, Center of Excellence for Advanced Science, Renewable Energy Group, Cairo (Egypt); Badr, M.A. [Mechanical Engineering Department, Cairo (Egypt); Madian, M. [Physical Chemistry Department, National Research Center, Center of Excellence for Advanced Science, Renewable Energy Group, Cairo (Egypt)

    2010-05-15T23:59:59.000Z

    Single phase MnPS{sub 3} powder was prepared by solid state reaction between Mn, S and P carried out at 650 deg. C in evacuated silica tube. The structure, morphology and sorption characteristics of the prepared solid were investigated. The results revealed that the obtained MnPS{sub 3} compound was capable of adsorbing 3.5 wt% hydrogen at -193 deg. C and a pressure of 30 bar. Little amount of hydrogen (0.07 wt%) was adsorbed at room temperature. The hydrogen adsorption/desorption cycles at various temperatures did not result in irreversible chemical structural changes of the MnPS{sub 3} compound, but the microstructure after hydrogen cycling diminished and became finer. - Graphical abstract: Atomic building of MPS{sub 3}

  2. Mn Monolayer Modified Rh for Syngas-to-Ethanol Conversion: A First-Principles Study

    SciTech Connect (OSTI)

    Li, Fengyu [University of Puerto Rico; Jiang, Deen [ORNL; Zeng, X.C. [University of Nebraska, Lincoln; Chen, Zhongfang [University of Puerto Rico

    2012-01-01T23:59:59.000Z

    Rh is unique in its ability to convert syngas to ethanol with the help of promoters. We performed systematic first-principles computations to examine the catalytic performance of pure and Mn modified Rh(100) surfaces for ethanol formation from syngas. CO dissociation on the surface as well as CO insertion between the chemisorbed CH{sub 3} and the surface are the two key steps. The CO dissociation barrier on the Mn monolayer modified Rh(100) surface is remarkably lowered by {approx}1.5 eV compared to that on Rh(100). Moreover, the reaction barrier of CO insertion into the chemisorbed CH{sub 3} group on the Mn monolayer modified Rh(100) surface is 0.34 eV lower than that of methane formation. Thus the present work provides new mechanistic insight into the role of Mn promoters in improving Rh's selectivity to convert syngas to ethanol.

  3. Magnetism of NiMn2O4-Fe3O4 spinel interfaces

    E-Print Network [OSTI]

    Nelson-Cheeseman, B. B.

    2007-01-01T23:59:59.000Z

    Magnetism of NiMn 2 O 4 –Fe 3 O 4 spinel interfaces B. B.2. Element-specific magnetism of Fe 3 O 4 /NMO interface inin these structures, 6 the magnetism near the isostructural

  4. Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

    SciTech Connect (OSTI)

    Nicholson, Don M [ORNL; Odbadrakh, Khorgolkhuu [ORNL; Rios, Orlando [ORNL; Hodges, Jason P [ORNL; Ludtka, Gerard Michael [ORNL; Porter, Wallace D [ORNL; Sefat, A. S. [Oak Ridge National Laboratory (ORNL); Rusanu, Aurelian [ORNL; Evans III, Boyd Mccutchen [ORNL

    2012-01-01T23:59:59.000Z

    Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system have been explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering (LSMS) method to explore the magnetic states responsible for the magnet-caloric effect in this material. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy were investigated using differential scanning calorimetry (DSC) and superconducting quantum interference device (SQUID). Neutron scattering experiments were performed to observe the structural and magnetic phase transformations at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on alloys of Ni-Mn-Ga and Ni-Mn-Ga-Cu-Fe. Data from the observations are discussed in comparison with the computational studies.

  5. DOI: 10.1002/ejic.200700164 Chlorido-Bridged MnII

    E-Print Network [OSTI]

    Gao, Song

    geometry sharing an equatorial-to-axial edge with parallel equatorial planes. The hydrogen bonds be,[3] dicyanamide,[4] and car- boxylate.[5] Ferromagnetic exchange coupling among these MnII compounds

  6. Above room-temperature ferromagnetism of Mn delta-doped GaN nanorods

    SciTech Connect (OSTI)

    Lin, Y. T.; Wadekar, P. V.; Kao, H. S.; Chen, T. H.; Chen, Q. Y.; Tu, L. W., E-mail: lwtu@faculty.nsysu.edu.tw [Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Huang, H. C.; Ho, N. J. [Department of Materials and Optoelectronic Science and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

    2014-02-10T23:59:59.000Z

    One-dimensional nitride based diluted magnetic semiconductors were grown by plasma-assisted molecular beam epitaxy. Delta-doping technique was adopted to dope GaN nanorods with Mn. The structural and magnetic properties were investigated. The GaMnN nanorods with a single crystalline structure and with Ga sites substituted by Mn atoms were verified by high-resolution x-ray diffraction and Raman scattering, respectively. Secondary phases were not observed by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. In addition, the magnetic hysteresis curves show that the Mn delta-doped GaN nanorods are ferromagnetic above room temperature. The magnetization with magnetic field perpendicular to GaN c-axis saturates easier than the one with field parallel to GaN c-axis.

  7. Perpendicular exchange bias effect in sputter-deposited CoFe/IrMn bilayers

    SciTech Connect (OSTI)

    Chen, J. Y., E-mail: chenjy02@gmail.com; Thiyagarajah, Naganivetha; Xu, H. J.; Coey, J. M. D. [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland)

    2014-04-14T23:59:59.000Z

    CoFe/IrMn bilayers with perpendicular magnetization for various IrMn layer thicknesses exhibit unusual two-step hysteresis loops with both positive and negative loop shifts. Observed at room temperature in the as-grown state, they provide direct evidence of large antiferromagnetic domain formation at the IrMn interface. The exchange bias field reaches 100?mT with an IrMn layer thickness of 4?nm after field annealing at 200?°C–300?°C in 800?mT, which is at least three times as large as the coercivity, and may be useful for reference layers of spin-valves or magnetic tunnel junctions with perpendicular magnetic anisotropy.

  8. Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past water-column

    E-Print Network [OSTI]

    Wehrli, Bernhard

    Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past online 22 June 2013 Abstract Here, we present sedimentological, trace metal, and molecular evidence underscores the value of combining sedimentological, geochemical, and microbiological approaches

  9. Reactivity of Pb(II) at the Mn(III,IV) (Oxyhydr)Oxide-Water Interface

    E-Print Network [OSTI]

    Sparks, Donald L.

    , the reactivity of lead (Pb(II)) on naturally occurring Mn(III,IV) (oxyhydr)oxide minerals was evaluated using to suggest oxidation as an operative sorption mechanism. Lead appeared to coordinate to vacancy sitesReactivity of Pb(II) at the Mn(III,IV) (Oxyhydr)Oxide-Water Interface C H R I S T O P H E R J . M

  10. Effect of MnAs/GaAs(001) film accommodations on the phase-transition temperature

    SciTech Connect (OSTI)

    Iikawa, F.; Brasil, M.J.S.P.; Couto, O.D.D.; Adriano, C.; Giles, C.; Daeweritz, L. [Instituto de Fisica 'Gleb Wataghin', UNICAMP, Campinas-SP, C.P. 6165, 13083-970 (Brazil); Instituto de Fisica 'Gleb Wataghin', UNICAMP, Campinas-SP, C.P. 6165, 13083-970, Brazil and Laboratorio Nacional de Luz Sincrotron, CP-6192, 13084-971 Campinas-SP (Brazil); Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2004-09-20T23:59:59.000Z

    The phase-transition temperature of MnAs epitaxial films grown by molecular-beam epitaxy on GaAs(001) with different crystalline accommodations was studied by specular and grazing incidence x-ray diffraction. The transition temperature of MnAs films with tilted hexagonal c-axis orientations with respect to the GaAs substrate is higher than the most investigated nontilted films and reaches a value above room temperature, which is more suitable for device applications.

  11. (In,Mn)As quantum dots: Molecular-beam epitaxy and optical properties

    SciTech Connect (OSTI)

    Bouravleuv, A. D., E-mail: bour@mail.ioffe.ru; Nevedomskii, V. N. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Ubyivovk, E. V. [St. Petersburg State University (Russian Federation)] [St. Petersburg State University (Russian Federation); Sapega, V. F. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Khrebtov, A. I. [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation)] [St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation); Samsonenko, Yu. B.; Cirlin, G. E.; Ustinov, V. M. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-08-15T23:59:59.000Z

    Self-assembled (In,Mn)As quantum dots are synthesized by molecular-beam epitaxy on GaAs (001) substrates. The experimental results obtained by transmission electron microscopy show that doping of the central part of the quantum dots with Mn does not bring about the formation of structural defects. The optical properties of the samples, including those in external magnetic fields, are studied.

  12. Hydrothermal synthesis of Mn vanadate nanosheets and visible-light photocatalytic performance for the degradation of methyl blue

    SciTech Connect (OSTI)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn; Xie, Y.K.; Pei, Y.Q.; Jiang, Y.X.; Yu, H.Y.; Cai, Z.Y.

    2013-07-15T23:59:59.000Z

    Graphical abstract: - Highlights: • Mn vanadate nanosheets have been synthesized by simple hydrothermal process. • The formation of Mn vanadate nanosheets can be controlled by growth conditions. • Mn vanadate nanosheets exhibit good photocatalytic activities for methyl blue. - Abstract: Mn vanadate nanosheets have been synthesized via a facile hydrothermal route using ammonium metavanadate and Mn acetate as the raw materials, polyvinyl pyrrolidone (PVP) as the surfactant. X-ray diffraction (XRD) shows that the Mn vanadate nanosheets are composed of monoclinic MnV{sub 2}O{sub 6} phase. Scanning electron microscopy (SEM) observation indicates that the nanosheets have the average thickness of about 50 nm, length of 2–10 ?m and width of 800 nm to 2 ?m. The growth process of the Mn vanadate nanosheets has also been discussed based on the analysis of the roles of the growth conditions on the formation of the Mn vanadate nanosheets. The nanosheets show good photocatalytic activities for the degradation of methylene blue (MB) under visible light irradiation. About 72.96% MB can be degraded after visible light irradiation for 1 h over 10 mg Mn vanadate nanosheets in 10 mL MB solution with the concentration of 10 mg L{sup ?1}.

  13. Magneto acoustical emission in nanocrystalline Mn–Zn ferrites

    SciTech Connect (OSTI)

    Praveena, K., E-mail: praveenaou@gmail.com [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Department of Physics, Osmania University, Hyderabad 500007 (India); Murthty, S.R. [Department of Physics, Osmania University, Hyderabad 500007 (India)

    2013-11-15T23:59:59.000Z

    Graphical abstract: Mn{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto-acoustic emission (MAE) activity along hysteresis loop is proportional to the hysteresis losses during the same loop. This law has been verified on series of polycrystalline ferrites and found that the law is valid whatever the composition, the grain size and temperature. It is also found that the domain wall creation/or annihilation processes are the origin of the MAE. - Highlights: • The AE been measured along the hysteresis loops from 80 K to Curie temperature. • The MAE activity along hysteresis loop is proportional to P{sub h} during the same loop. • It is found that the domain wall creation/or annihilation processes are the origin of the MAE. - Abstract: Mn{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} powders were prepared by microwave hydrothermal method. The powders were characterized by X-ray diffraction, transmission electron microscope. The powders were sintered at different temperatures 400, 500, 600, 700, 800 and 900 °C/30 min using microwave sintering method. The grain size was estimated by scanning electron microscope. The room temperature dielectric and magnetic properties were studied in the frequency range (100 kHz–1.8 GHz). The magnetization properties were measured upto 1.5 T. The acoustic emission has been measured along the hysteresis loops from 80 K to Curie temperature. It is found that the magneto-acoustic emission (MAE) activity along hysteresis loop is proportional to the hysteresis losses during the same loop. This law has been verified on series of polycrystalline ferrites and found that the law is valid whatever the composition, the grain size and temperature. It is also found that the domain wall creation/or annihilation processes are the origin of the MAE.

  14. Magnetic Order and Ferroelectricity in RMnO3 Multiferroic Manganites: Coupline Between R- and Mn-spins

    SciTech Connect (OSTI)

    Aliouane, N.; Prokhnenko, O; Feyerherm, R; Mostovoy, M; Strempfer, J; Habicht, K; Rule, K; Dudzik, E; Wolter, A; et. al.

    2008-01-01T23:59:59.000Z

    Combining polarized and unpolarized neutron scattering techniques with x-ray resonant magnetic scattering we have studied the coupling between the Mn- and R-spin-ordering in the multiferroic RMnO3, R = Tb and Dy. Polarized neutron diffraction reveals the moment orientation associated with the various modes describing the complex magnetic ordering observed in TbMnO3, while neutron diffraction in high magnetic fields allows the identification of the origin (Mn versus Tb) of the various modes. In this way we identify significant Cx and Fz contributions from Tb arising from the coupling of Tb moments to the Mn cycloidal ordering. The x-ray studies give further insight into this coupling. In the ferroelectric phase, both TbMnO3 and DyMnO3 show an induced ordering of the R-ion with a propagation vector clamped to the Mn ordering. While in TbMnO3 this clamping leads to a ground state in which the two propagation vectors tTb and tMn obey the relation 3tTb-tMn = 1, in DyMnO3 the ferroelectric polarization is effectively enhanced. The theoretical analysis of these effects not only explains the observed behavior for R = Tb and Dy but can also be applied to understand the Mn-R interaction in the related compounds with R = Gd and Ho. Finally we show both experimentally and theoretically how the Mn-R coupling can enhance the ferroelectric polarization in this manganite's multiferroics.

  15. Magnetic properties and loss separation in iron-silicone-MnZn ferrite soft magnetic composites

    SciTech Connect (OSTI)

    Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zou, Chao; Yang, Jun; Dong, Juan [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing (China)

    2013-12-16T23:59:59.000Z

    This paper investigates the magnetic and structural properties of iron-based soft magnetic composites coated with silicone-MnZn ferrite hybrid. The organic silicone resin was added to improve the flexibility of the insulated iron powder and causes better adhesion between particles to increase the mechanical properties. Scanning electron microscopy and distribution maps show that the iron particle surface is covered with a thin layer of silicone-MnZn ferrite. Silicone-MnZn ferrite coated samples have higher permeability when compared with the non-magnetic silicone resin coated compacts. The real part of permeability increases by 34.18% when compared with the silicone resin coated samples at 20 kHz. In this work, a formula for calculating the total loss component by loss separation method is presented and finally the different parts of total losses are calculated. The results show that the eddy current loss coefficient is close to each other for the silicone-MnZn ferrite, silicone resin and MnZn ferrite coated samples (0.0078MnZn ferrite coated sample (k{sub 2} =1.4058) in comparison with other samples.

  16. Synthesis and characterization of nanoparticulate MnS within the pores of mesoporous silica

    SciTech Connect (OSTI)

    Barry, Louse; Copley, Mark [Department of Chemistry, University College Cork, Cork (Ireland); Holmes, Justin D. [Department of Chemistry, University College Cork, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Otway, David J. [Department of Chemistry, University College Cork, Cork (Ireland); Kazakova, Olga [National Physical Laboratory, Teddington (United Kingdom); Morris, Michael A. [Department of Chemistry, University College Cork, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland)], E-mail: m.morris@ucc.ie

    2007-12-15T23:59:59.000Z

    Mesoporous silica was loaded with nanoparticulate MnS via a simple post-synthesis treatment. The mesoporous material that still contained surfactant was passivated to prevent MnS formation at the surface. The surfactant was extracted and a novel manganese ethylxanthate was used to impregnate the pore network. This precursor thermally decomposes to yield MnS particles that are smaller or equal to the pore size. The particles exhibit all three common polymorphs. The passivation treatment is most effective at lower loadings because at the highest loadings (SiO{sub 2}:MnS molar ratio of 6:1) large particles (>50 nm) form at the exterior of the mesoporous particles. The integrity of the mesoporous network is maintained through the preparation and high order is maintained. The MnS particles exhibit unexpected ferromagnetism at low temperatures. Strong luminescence of these samples is observed and this suggests that they may have a range of important application areas. - Graphical abstract: A novel manganese ethylxanthate precursor was used to impregnate the pore network of mesoporous silica and was decomposed to yield MnS particles smaller or equal to the pore size. The particles exhibit all three common polymorphs, demonstrate unexpected ferromagnetism at low temperatures and display a strong luminescence.

  17. Inverse magnetocaloric effect in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys

    SciTech Connect (OSTI)

    Singh, Sanjay, E-mail: sanju8419@gmail.com; Barman, S. R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Esakki Muthu, S.; Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Senyshyn, A. [Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, Lichtenbergstrasse 1, 85747 Garching b. München (Germany); Rajput, P. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble (France); Suard, E. [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2014-02-03T23:59:59.000Z

    Inverse magnetocaloric effect is demonstrated in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys. The entropy change at the martensite transition is larger in Mn{sub 1.75}Ni{sub 1.25}Ga, and it increases linearly with magnetic field in both the specimens. Existence of inverse magnetocaloric effect is consistent with the observation that magnetization in the martensite phase is smaller than the austenite phase. Although the Mn content is smaller in Mn{sub 1.75}Ni{sub 1.25}Ga, from neutron diffraction, we show that the origin of inverse magnetocaloric effect is the antiferromagnetic interaction between the Mn atoms occupying inequivalent sites.

  18. Beta-decay of Mn-65 to Fe-65

    E-Print Network [OSTI]

    Olaizola, B; Mach, H; Aprahamian, A; Briz, J A; Cal-Gonzalez, J; Ghita, D; Koster, U; Kurcewicz, W; Lesher, S R; Pauwels, D; Picado, E; Poves, A; Radulov, D; Simpson, G S; Udias, J M

    2013-01-01T23:59:59.000Z

    The low energy structure of Fe-65 has been studied by means of gamma- and fast-timing spectroscopy. A level scheme of Fe-65 populated following the beta-decay of Mn-65 was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the beta-decaying isomer in Fe-65 has been precisely determined at 393.7(2) keV. The beta delayed neutron emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four gamma-rays and four excited states in Fe-64 were identified as being populated following the beta-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the Advanced Time-Delayed Method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations and the systematics of the region.

  19. Synthesis of Li{sub (x)}Na{sub (2-x)}Mn{sub 2}S{sub 3} and LiNaMnS{sub 2} through redox-induced ion exchange reactions

    SciTech Connect (OSTI)

    Luthy, Joshua A.; Goodman, Phillip L. [Department of Chemistry and Biochemistry, Texas State University-San Marcos, 601 University Drive, San Marcos, TX 78666 (United States); Martin, Benjamin R. [Department of Chemistry and Biochemistry, Texas State University-San Marcos, 601 University Drive, San Marcos, TX 78666 (United States)], E-mail: bmartin@txstate.edu

    2009-03-15T23:59:59.000Z

    Na{sub 2}Mn{sub 2}S{sub 3} was oxidatively deintercalated using iodine in acetonitrile to yield Na{sub 1.3}Mn{sub 2}S{sub 3}, with lattice constants nearly identical to that of the reactant. Lithium was then reductively intercalated into the oxidized product to yield Li{sub 0.7}Na{sub 1.3}Mn{sub 2}S{sub 3}. When heated, this metastable compound decomposed to form a new crystalline compound, LiNaMnS{sub 2}, along with MnS and residual Na{sub 2}Mn{sub 2}S{sub 3}. Single crystal X-ray diffraction structural analysis of LiNaMnS{sub 2} revealed that this compound crystallizes in P-3m1 with cell parameters a=4.0479(6) A, c=6.7759(14) A, V=96.15(3) A{sup 3} (Z=1, wR2=0.0367) in the NaLiCdS{sub 2} structure-type. - Graphical abstract: Structure of LiNaMnS{sub 2}. Li and Mn are statistically distributed in edge-shared tetrahedral environments linked into infinite planes. Sodium ions occupy interlayer sites.

  20. Magnetic properties of a metal-organic antiferromagnet Mn,,hfipbb...py,,H2O...0.5

    E-Print Network [OSTI]

    Li, Jing

    Magnetic properties of a metal-organic antiferromagnet Mn,,hfipbb...py,,H2O...0.5 Tan Yuena and C Jersey 08854 Presented on 2 November 2005; published online 18 April 2006 Mn hfipbb py H2O 0.5 H2hfipbb=4 as on powder samples of Mn hfipbb py H2O 0.5. Antiferromagnetic ordering was observed below a transition

  1. Synthesis of spherical LiMnPO{sub 4}/C composite microparticles

    SciTech Connect (OSTI)

    Bakenov, Zhumabay [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)] [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Taniguchi, Izumi, E-mail: taniguchi.i.aa@m.titech.ac.jp [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)] [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2011-08-15T23:59:59.000Z

    Highlights: {yields} We could prepare LiMnPO{sub 4}/C composites by a novel preparation method. {yields} The LiMnPO{sub 4}/C composites were spherical particles with a mean diameter of 3.65 {mu}m. {yields} The LiMnPO{sub 4}/C composite cathode exhibited 112 mAh g{sup -1} at 0.05 C. {yields} It also showed a good rate capability up to 5 C at room temperature and 55 {sup o}C. -- Abstract: Spherical LiMnPO{sub 4}/C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO{sub 4}/C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was identified as a single phase orthorhombic structure of LiMnPO{sub 4} and spherical powders with a geometric mean diameter of 3.65 {mu}m and a geometric standard deviation of 1.34. The electrochemical cells contained the spherical LiMnPO{sub 4}/C microparticles exhibited first discharge capacities of 112 and 130 mAh g{sup -1} at 0.05 C at room temperature and 55 {sup o}C, respectively. These also showed a good rate capability up to 5 C at room temperature and 55 {sup o}C.

  2. Supercapacitor behavior of ?-MnMoO{sub 4} nanorods on different electrolytes

    SciTech Connect (OSTI)

    Purushothaman, K.K., E-mail: purushoth_gri@yahoo.co.in [Department of Physics, TRP Engineering College (SRM Group), Irungalur, Trichy, Tamilnadu (India); Cuba, M. [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India)] [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India); Muralidharan, G., E-mail: muralg@rediffmail.com [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India)

    2012-11-15T23:59:59.000Z

    Graphical abstract: SEM image of ?-MnMoO{sub 4} nanorods on FTO substrate. Highlights: ? Synthesis of ?-MnMoO{sub 4} nanorods by spin coating method. ? First study on the effect of electrolyte on the pseudocapacitance behavior. ? ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g. ? At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: ?-MnMoO{sub 4} nanorods were prepared on conducting glass substrate via sol–gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the ?-MnMoO{sub 4} nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H{sub 2}SO{sub 4}) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of ?-MnMoO{sub 4} in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M–O and Mo–O–Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H{sub 2}SO{sub 4} electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H{sub 2}SO{sub 4}.

  3. Enhanced ferromagnetic order in Sr{sub 4}Mn{sub 3}O{sub 3}(GeO{sub 4}){sub 3} featuring canted [MnO{sub 4}]{sub ?} spin chains of mixed-valent Mn(III)/Mn(IV). Aliovalent substitution of the Sr{sub 4?x}Ln{sub x}Mn{sup III}{sub 2+x}Mn{sup IV}{sub 1?x}O{sub 3}(GeO{sub 4}){sub 3} solid-solution

    SciTech Connect (OSTI)

    West, J. Palmer; Sulejmanovic, Dino [Department of Chemistry, Clemson University, Clemson, SC 29634 (United States); Becht, Gregory [E. I. du Pont, Wilmington, DE 19880-0500 (United States); He, Jian; Hitchcock, Dale [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Yan, Yonggao [Wuhan University of Technology, Wuhan 430070 (China); Hwu, Shiou-Jyh, E-mail: shwu@clemson.edu [Department of Chemistry, Clemson University, Clemson, SC 29634 (United States)

    2013-10-15T23:59:59.000Z

    Crystals of Sr{sub 4?x}Ln{sub x}Mn{sub 3}O{sub 3}(GeO{sub 4}){sub 3} (x=0; x?0.15 for Ln=La, Pr, Nd, Sm. Eu, Gd, Dy; x?0.3 for Ln=Gd) were isolated upon using high-temperature, solid-state methods in molten-salt media. These compounds are isostructural with the previously reported Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3} (Ln=La, Sm, Gd) series that contains the same [MnO{sub 4}]{sub ?} spin chains. The synthesis of the Sr{sub 4}Mn{sub 3}O{sub 3}(GeO{sub 4}){sub 3} (x=0) phase was carried out by a double aliovalent substitution with respect to the Sr{sup 2+} and Ge{sup 4+} ions that replace Na{sup +}/Ln{sup 3+} and As{sup 5+} in Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3}, respectively. The title series contains mixed-valent Mn(III)/Mn(IV) and shows a limited range of solid solution, both of which were not observed in the previously reported Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3} series. To form the Sr{sub 4?x}Ln{sub x}Mn{sub 3}O{sub 3}(GeO{sub 4}){sub 3} solid solution, one of the Sr{sup 2+} sites, i.e., the original Ln-site in Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3}, is partially substituted by Ln{sup 3+} in a statistical disorder of Sr{sub 1?x}/Ln{sub x}. Initial magnetic investigations of selected derivatives reveal higher ferromagnetic ordering temperatures than those reported for the Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3} series, presumably attributed to a lesser degree of canting as a result of introducing non-Jahn–Teller Mn{sup 4+} ions. Also intriguing is the observation of multiple anomalies at low temperatures which appear to be of electronic origins. - Graphical abstract: Sr{sub 4?x}Ln{sub x}Mn(III){sub 2+x}Mn(IV){sub 1?x}O{sub 3}(GeO{sub 4}){sub 3}. Display Omitted - Highlights: • Double aliovalent substitution: Sr{sub 4}Mn{sub 3}O{sub 3}(GeO{sub 4}){sub 3} with respect to Na{sub 3}LnMn{sub 3}O{sub 3}(AsO{sub 4}){sub 3}. • Solid solution with respect to statistical disorder of Sr{sub 1?x}Ln{sub x} in one of the two Sr sites. • Mn{sup 3+}/Mn{sup 4+} magnetic ions are spatially arranged in a triangular kagomé fashion. • Enhanced ferromagnetic ordering attributed to doping non-Jahn–Teller Mn{sup 4+}.

  4. Novel Solar Energy Conversion Materials by Design of Mn(II) Oxides

    SciTech Connect (OSTI)

    Lany, S.; Peng, H.; Ndione, P.; Zakutayev, A.; Ginley, D. S.

    2013-01-01T23:59:59.000Z

    Solar energy conversion materials need to fulfill simultaneously a number of requirements in regard of their band-structure, optical properties, carrier transport, and doping. Despite their desirable chemical properties, e.g., for photo-electrocatalysis, transition-metal oxides usually do not have desirable semiconducting properties. Instead, oxides with open cation d-shells are typically Mott or charge-transfer insulators with notoriously poor transport properties, resulting from large effective electron/hole masses or from carrier self-trapping. Based on the notion that the electronic structure features (p-d interaction) supporting the p-type conductivity in d10 oxides like Cu2O and CuAlO2 occurs in a similar fashion also in the d5 (high-spin) oxides, we recently studied theoretically the band-structure and transport properties of the prototypical binary d5 oxides MnO and Fe2O3 [PRB 85, 201202(R)]. We found that MnO tends to self-trap holes by forming Mn+III, whereas Fe2O3 self-traps electrons by forming Fe+II. However, the self-trapping of holes is suppressed by when Mn is tetrahedrally coordinated, which suggests specific routes to design novel solar conversion materials by considering ternary Mn(II) oxides or oxide alloys. We are presenting theory, synthesis, and initial characterization for these novel energy materials.

  5. Carbon/lambda-MnO{sub 2} composites for supercapacitor electrodes

    SciTech Connect (OSTI)

    Malak-Polaczyk, A., E-mail: agnieszka-malak@wp.p [Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Piotrowo 3, 60-695 Poznan (Poland); Institut de Sciences des Materiaux de Mulhouse, CNRS LRC 7228, 15 Rue Starcky, 68057 Mulhouse (France); Matei-Ghimbeu, C.; Vix-Guterl, C. [Institut de Sciences des Materiaux de Mulhouse, CNRS LRC 7228, 15 Rue Starcky, 68057 Mulhouse (France); Frackowiak, E. [Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Piotrowo 3, 60-695 Poznan (Poland)

    2010-04-15T23:59:59.000Z

    In the present work a composite of carbon with lambda-MnO{sub 2} have been synthesized by a simple two-step route. In the first step, to obtain LiMn{sub 2}O{sub 4}/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of lambda-MnO{sub 2}/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed lambda-MnO{sub 2} particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the lambda-MnO{sub 2} is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation. - Comparison of capacitance characteristics for initial carbon and synthesised composites for CB in 1 mol L{sup -1} Na{sub 2}SO{sub 4} solution.

  6. The resistance to cavitation erosion of CrMnN stainless steels

    SciTech Connect (OSTI)

    Fu, W.T. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; [Harbin Inst. of Tech. (China); Jing, T.F.; Zheng, Y.Z. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; Yang, Y.B. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; [Bohai Aluminum Industries Co., Ltd., Qinhuangdao (China); Yao, M. [Harbin Inst. of Tech. (China)] [Harbin Inst. of Tech. (China)

    1998-12-01T23:59:59.000Z

    The resistance to cavitation erosion (CE) was measured using a magnetostrictive device and a rotating disk device for some CrMnN stainless steels (Chinese patent ZL 90 1 02197.0). The microstructural changes in the surface layer before and after CE were analyzed by use of Mossbauer spectra. Results show that the resistance to CE of duplex austenitic-martensitic CrMnN stainless steels is much better than that of ZG0Cr13Ni4-6Mo and ZG0Cr16Ni5Mo steel, which are in common use for hydraulic turbine runners. The metastable austenite and its changes in the process of CE are the key factors why the CrMnN stainless steels have excellent resistance to cavitation erosion.

  7. Ferromagnetism and the electronic band structure in (Ga,Mn)(Bi,As) epitaxial layers

    SciTech Connect (OSTI)

    Yastrubchak, O., E-mail: yastrub@hektor.umcs.lublin.pl [Institute of Physics, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 1, 20-031 Lublin (Poland); Institute of Semiconductor Physics, National Academy of Sciences, 41 pr. Nauki, 03028 Kyiv (Ukraine); Sadowski, J. [MAX-IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Gluba, L.; ?uk, J.; Kulik, M. [Institute of Physics, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 1, 20-031 Lublin (Poland); Domagala, J. Z.; Andrearczyk, T.; Wosinski, T. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Rawski, M. [Analytical Laboratory, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 3, 20-031 Lublin (Poland)

    2014-08-18T23:59:59.000Z

    Impact of Bi incorporation into (Ga,Mn)As layers on their electronic- and band-structures as well as their magnetic and structural properties has been studied. Homogenous (Ga,Mn)(Bi,As) layers of high structural perfection have been grown by the low-temperature molecular-beam epitaxy technique. Post-growth annealing treatment of the layers results in an improvement of their structural and magnetic properties and an increase in the hole concentration in the layers. The modulation photoreflectance spectroscopy results are consistent with the valence-band model of hole-mediated ferromagnetism in the layers. This material combines the properties of (Ga,Mn)As and Ga(Bi,As) ternary compounds and offers the possibility of tuning its electrical and magnetic properties by controlling the alloy composition.

  8. Photoluminescence properties of Tb-Eu-Mn-codoped fluoroborate glasses under ?-irradiation

    SciTech Connect (OSTI)

    Hari Babu, B.; Ravi Kanth Kumar, V. V. [Department of Physics, Pondicherry University, R. V. Nagar, Kalapet, Puducherry 605014 (India)] [Department of Physics, Pondicherry University, R. V. Nagar, Kalapet, Puducherry 605014 (India)

    2013-09-28T23:59:59.000Z

    We report here an energy transfer from Tb{sup 3+} to Eu{sup 3+}, Mn{sup 2+} and Eu{sup 2+} to Tb{sup 3+} and Mn{sup 2+} for an un-irradiated and ?-irradiated B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-Na{sub 2}O-SrF{sub 2} glass samples, respectively. The blue emission from Eu{sup 2+} ions as well as green and red emission from Tb{sup 3+}, Eu{sup 3+}, and Mn{sup 2+} ions will contribute to the generation of white light while excited at 339 nm using a xenon lamp. Furthermore, the chromaticity color coordinates, correlated color temperature, and quantum efficiency parameters are calculated for all the glass samples, and their relative variations with respect to ?-irradiation dose are presented.

  9. Shell Model for Atomistic Simulation of Lithium Diffusion in Mixed Mn/Ti Oxides

    SciTech Connect (OSTI)

    Kerisit, Sebastien N.; Chaka, Anne M.; Droubay, Timothy C.; Ilton, Eugene S.

    2014-10-23T23:59:59.000Z

    Mixed Mn/Ti oxides present attractive physicochemical properties such as their ability to accommodate Li for application in Li-ion batteries. In this work, atomic parameters for Mn were developed to extend an existing shell model of the Li-Ti-O system and allow simulations of pure and lithiated Mn and mixed Mn/Ti oxide polymorphs. The shell model yielded good agreement with experimentally-derived structures (i.e. lattice parameters and inter-atomic distances) and represented an improvement over existing potential models. The shell model was employed in molecular dynamics (MD) simulations of Li diffusion in the 1×1 c direction channels of LixMn1 yTiyO2 with the rutile structure, where 0 ? x ? 0.25 and 0 ? y ? 1. In the infinite dilution limit, the arrangement of Mn and Ti ions in the lattice was found to have a significant effect on the activation energy for Li diffusion in the c channels due to the destabilization of half of the interstitial octahedral sites. Anomalous diffusion was demonstrated for Li concentrations as low as x = 0.125, with a single Li ion positioned in every other c channel. Further increase in Li concentration showed not only the substantial effect of Li-Li repulsive interactions on Li mobility but also their influence on the time dependence of Li diffusion. The results of the MD simulations can inform intrinsic structure-property relationships for the rational design of improved electrode materials for Li-ion batteries.

  10. DOI: 10.1002/ente.201200009 Examining the CuMnO Spinel System as an Oxygen

    E-Print Network [OSTI]

    Azad, Abdul-Majeed

    of CO2 in the atmosphere. Among these, carbon capture and storage (CCS) is one of the most attractive to CuO­Cu2O and Mn2O3­Mn3O4 as potential CLOU materials. [a] Prof. A.-M. Azad Department of Chemical

  11. Enhanced Li+ ion transport in LiNi0.5Mn1.5O4 through Control...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Li+ ion transport in LiNi0.5Mn1.5O4 through Control of Site Disorder. Enhanced Li+ ion transport in LiNi0.5Mn1.5O4 through Control of Site Disorder. Abstract: High voltage spinel...

  12. 48 28th ANNUAL eMS CHROMIUM(llI) INDUCED SOLID PHASE TRANSFORMATION OF o-Mn02

    E-Print Network [OSTI]

    Sparks, Donald L.

    48 28th ANNUAL eMS CHROMIUM(llI) INDUCED SOLID PHASE TRANSFORMATION OF o-Mn02 Fendorf S pathways which will allow for transformations between oxidation states (redox reactions). Manganese oxides implications for environmental quality. The highly redox reactive a-Mn02 is transformed into a redox stable

  13. Ultrathin Spinel LiMn2O4 Nanowires as High Power Cathode Materials for Li-Ion Batteries

    E-Print Network [OSTI]

    Cui, Yi

    Ultrathin Spinel LiMn2O4 Nanowires as High Power Cathode Materials for Li-Ion Batteries Hyun diameters less than 10 nm and lengths of several micrometers. Galvanostatic battery testing showed that Li, lithium ion battery, LiMn2O4 nanowires, high power density, Jahn-Teller distortion T he high energy

  14. Charge and magnetic states of Mn-, Fe-, and Co-doped monolayer MoS{sub 2}

    SciTech Connect (OSTI)

    Lin, Xianqing [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023 (China); Ni, Jun, E-mail: junni@mail.tsinghua.edu.cn [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China)

    2014-07-28T23:59:59.000Z

    First-principles calculations have been performed to investigate the electronic and magnetic properties of monolayer MoS{sub 2} substitutionally doped with Mn, Fe, and Co in possible charge states (q). We find that the Mn, Fe, and Co dopants substituting for a Mo atom in monolayer MoS{sub 2} (Mn@Mo, Fe@Mo, and Co@Mo) are all magnetic in their neutral and charge states except in the highest positive charge states. Mn@Mo, Fe@Mo, and Co@Mo have the same highest negative charge states of q=?2 for chemical potential of electron just below the conduction band minimum, which corresponds to the electron doping. In the q=?2 state, Mn@Mo has a much larger magnetic moment than its neutral state with the antiferromagnetic coupling between the Mn dopant and its neighboring S atoms maintained, while Fe@Mo and Co@Mo have equal or smaller magnetic moments than their neutral states. The possible charge states of Mn@Mo, Fe@Mo, and Co@Mo and the variation of the magnetic moments for different dopants and charge states are due to the change of the occupation and energy of the anti-bonding defect levels in the band gap. The rich magnetic properties of the neutral and charge states suggest possible realization of the substitutionally Mn-, Fe-, and Co-doped monolayer MoS{sub 2} as dilute magnetic semiconductors.

  15. Polarization Resistance of La0.85Ca0.15MnO3 Cathodes for Solid...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Resistance of La0.85Ca0.15MnO3 Cathodes for Solid Oxide Fuel Cells (SOFCs) Measured Using Patterned Electrodes. Polarization Resistance of La0.85Ca0.15MnO3 Cathodes for Solid Oxide...

  16. MnPASS System Study Phase 2 Prepared for the Minnesota Department of Transportation by Cambridge Systematics, Inc. with SRF

    E-Print Network [OSTI]

    Minnesota, University of

    will be put in place during construction The Next Opportunity See Cayuga Project materials at: http://www.dot.state.mn.us/metro/projects/cayuga/indexPASS onto the Twin City Highway System · Identified a potential MnPASS system ­ Studied cost, operational provide increased trip reliability and user choice in a cost-effective manner (I-394) ­ New lower cost

  17. Effet de l'apport de phosphore, de carbonate de calcium et d'oligo-lments (Cu, Mn, Zn, B)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Agronomie Effet de l'apport de phosphore, de carbonate de calcium et d'oligo-éléments (Cu, Mn, Zn apports de phosphore, de carbonate de calcium et d'oligo-éléments (Mn, Cu, Zn, B), en vue de mieux celles de B lorsqu'on élève le pH par apport de carbonate de calcium; - l'accumulation préférentielle de

  18. First-principles study of magnetism in spinel MnO2 Dane Morgan and Billie Wang

    E-Print Network [OSTI]

    Ceder, Gerbrand

    First-principles study of magnetism in spinel MnO2 Dane Morgan and Billie Wang Department to calculate the ground state, transition tem- perature, and thermodynamic properties of magnetic excitations in spinel MnO2 . The magnetic interactions are mapped onto a Heisenberg model whose exchange interactions

  19. Determination of Mn valence states in mixed-valent manganates by XANES spectroscopy AlAin MAnceAu,1,

    E-Print Network [OSTI]

    Cedex 9, France 2 Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road and phyllomanganates with no or little Mn3+ in the MnO2 layer exhibit intensi- ties, shapes, and relative energy catalysis, hazardous waste remediation, and rechargeable battery technology (Thackeray 1997; Toupin et al

  20. Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

    SciTech Connect (OSTI)

    Behler, Anna [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany) [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Department of Physics, Institute for Solid State Physics, Dresden University of Technology, 01062 Dresden (Germany); Teichert, Niclas; Auge, Alexander; Hütten, Andreas [Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, 33501 Bielefeld (Germany)] [Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, 33501 Bielefeld (Germany); Dutta, Biswanath; Hickel, Tilmann [Max-Planck Institut für Eisenforschung, 40237 Düsseldorf (Germany)] [Max-Planck Institut für Eisenforschung, 40237 Düsseldorf (Germany); Waske, Anja [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany)] [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Eckert, Jürgen [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany) [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Institute of Materials Science, Dresden University of Technology, 01062 Dresden (Germany)

    2013-12-15T23:59:59.000Z

    A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni{sub 50}Mn{sub 32}Sn{sub 18} thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase.

  1. Relaxation of photoinduced spins and carriers in ferromagnetic InMnSb films

    SciTech Connect (OSTI)

    Nontapot, K.; Kini, R. N.; Gifford, A.; Merritt, T. R.; Khodaparast, G. A.; Wojtowicz, T.; Liu, X.; Furdyna, J. K. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2007-04-02T23:59:59.000Z

    The authors report time resolved measurements and control of photoinduced spin and carrier relaxations in InMnSb ferromagnetic films with 2% Mn content (grown by low-temperature molecular beam epitaxy) using femtosecond laser pulses, and compare them to analogous measurements on InBeSb and InSb films. In this work, magneto-optical Kerr effect and standard pump-probe techniques provided a direct measure of the photoexcited spin and carrier lifetimes, respectively. They observe decrease in relaxations times in the high laser fluence regime and an absence of temperature dependence of the relaxation times.

  2. Graphene in proximity to magnetic insulating LaMnO{sub 3}

    SciTech Connect (OSTI)

    Cheng, Guanghui; Wei, Laiming, E-mail: laiming@ustc.edu.cn, E-mail: cgzeng@ustc.edu.cn; Cheng, Long; Liang, Haixing; Zhang, Xiaoqiang; Li, Hui [Hefei National Laboratory for Physical Sciences at the Microscale (HFNL) and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yu, Guolin [Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083 (China); Zeng, Changgan, E-mail: laiming@ustc.edu.cn, E-mail: cgzeng@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale (HFNL) and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); International Center for Quantum Design of Functional Materials (ICQD), HFNL, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-09-29T23:59:59.000Z

    Proximity to functional substrates may enhance the coupling between the quantum degrees of freedom and thus develop nontrivial quantum effects in graphene. Here, we demonstrate the successful fabrication of graphene in proximity to atomically flat magnetic insulating LaMnO{sub 3} films. The insulating nature of the LaMnO{sub 3} films not only ensures the electronic transport only occur in the graphene layers but also allow them to serve as dielectric layers for gating. Transport measurements reveal anomalous behaviors, including asymmetrical longitudinal magnetoresistivity and nonlinear Hall effect. This work may pave a way toward the realization of intriguing quantum phases in graphene.

  3. Dynamical x-ray diffraction from an icosahedral Al-Pd-Mn quasicrystal

    SciTech Connect (OSTI)

    Kycia, S.

    1996-04-23T23:59:59.000Z

    Primary extinction effects in diffraction from single grains of Al-Pd- Mn, and presumably many other FCI alloys, may be significant and should be corrected for prior to use of diffraction data in structural determinations. Probes based on dynamical diffraction effects, such as x-ray standing wave fluorescence, multiple beam interference, and x-ray transmission topographs, may now be used to study the bulk and surface structure of some quasicrystals. The observation of dynamical diffraction from icosahedral Al-Pd-Mn is a striking confirmation of the fact that quasicrystals can present a degree of structural perfection comparable to that found in the best periodic intermetallic crystals.

  4. Quantum Critical Transition Amplifies Magnetoelastic Coupling in Mn[N(CN)2]2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brinzari, T. V.; Chen, P.; Sun, Q.-C.; Liu, J.; Tung, L.-C.; Wang, Y.; Schlueter, J. A.; Singleton, J.; Manson, J. L.; Whangbo, M.-H.; Litvinchuk, A. P.; Musfeldt, J. L.

    2013-06-01T23:59:59.000Z

    We report the discovery of a magnetic quantum critical transition in Mn[N(CN)2]2 that drives the system from a canted antiferromagnetic state to the fully polarized state with amplified magnetoelastic coupling as an intrinsic part of the process. The local lattice distortions, revealed through systematic phonon frequency shifts, suggest a combined MnN6 octahedra distortion+counterrotation mechanism that reduces antiferromagnetic interactions and acts to accommodate the field-induced state. These findings deepen our understanding of magnetoelastic coupling near a magnetic quantum critical point and away from the static limit.

  5. Structural transformations in Mn{sub 2}NiGa due to residual stress

    SciTech Connect (OSTI)

    Singh, Sanjay; Maniraj, M.; D'Souza, S. W.; Barman, S. R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Ranjan, R. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2010-02-22T23:59:59.000Z

    Powder x-ray diffraction study of Mn{sub 2}NiGa ferromagnetic shape memory alloy shows the existence of a 7M monoclinic modulated structure at room temperature (RT). The structure of Mn{sub 2}NiGa is found to be highly dependent on residual stress. For higher stress, the structure is tetragonal at RT, and for intermediate stress it is 7M monoclinic. However, only when the stress is considerably relaxed, the structure is cubic, as is expected at RT since the martensitic transition temperature is 230 K.

  6. MnO spin-wave dispersion curves from neutron powder diffraction

    SciTech Connect (OSTI)

    Goodwin, Andrew L.; Dove, Martin T. [Department of Earth Sciences, Cambridge University, Downing Street, Cambridge CB2 3EQ (United Kingdom); Tucker, Matthew G. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Keen, David A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

    2007-02-15T23:59:59.000Z

    We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

  7. A study of magnetic anisotropy energy in CuMn spin glass

    E-Print Network [OSTI]

    Allen, Christine Adele

    1986-01-01T23:59:59.000Z

    A STUDY OF MAGNETIC ANISOTROPY ENERGY IN CuMn SPIN GLASS A Thesis by CHRISTINE ADELE ALLEN Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1986... Major Subject: Physics A STUDY OF MAGNETIC ANISOTROPY ENERGY IN CuMn SPIN GLASS A Thesis by CHRISTINE ADELE ALLEN Approved as to style and content by: Thomas W. Adair, III (Chai man of Committee) Robert A. enefick (Member) Donald L. Parker...

  8. Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

    SciTech Connect (OSTI)

    Nicholson, Don M [ORNL; Odbadrakh, Khorgolkhuu [ORNL; Shassere, Benjamin [ORNL; Rios, Orlando [ORNL; Hodges, Jason P [ORNL; Ludtka, Gerard Michael [ORNL; Porter, Wallace D [ORNL; Safa-Sefat, Athena [ORNL; Rusanu, Aurelian [ORNL; Brown, Greg [ORNL; Evans III, Boyd Mccutchen [ORNL

    2014-01-01T23:59:59.000Z

    Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system are explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering method. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy are investigated using differential scanning calorimetry and superconducting quantum interference device. Experiments are performed at the Spallation Neutron Source at Oak Ridge National Laboratory to observe the structural and magnetic phase transformations.

  9. Spatial distribution of MnS inclusions in HY-100 steel

    SciTech Connect (OSTI)

    Everett, R.K. [Naval Research Lab., Washington, DC (United States). Multifunctional Materials Branch] [Naval Research Lab., Washington, DC (United States). Multifunctional Materials Branch; Geltmacher, A.B. [FM Technologies, Inc., Fairfax, VA (United States)] [FM Technologies, Inc., Fairfax, VA (United States)

    1999-02-05T23:59:59.000Z

    High strength steels have been shown to fail by a ductile fracture process which includes void nucleation, growth, and linking by coalescence and void sheeting. Since the voids are thought to nucleate at MnS inclusions and initial void nucleating strains are considered small, some relationship between the inclusion spatial distribution and the initial void spatial distribution appears reasonable. The initial void spatial distribution is desired for improved models of void growth and coalescence behavior. This paper reports on the density, and size and spatial distributions of MnS inclusions in an HY-100 steel.

  10. Effect of Ti doping on high pressure behavior of BiMn{sub 2}O{sub 5}

    SciTech Connect (OSTI)

    Pandey, K. K., E-mail: kkpandey@barc.gov.in; Poswal, H. K., E-mail: kkpandey@barc.gov.in; Sharma, Surinder M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 40008 (India); Kumar, Ravi [Centre for Materials Science and Engineering, National Institute of Technology, Hamirpur-177005 (India)

    2014-04-24T23:59:59.000Z

    Our high pressure x-ray diffraction studies on BiMn{sub 1.5}Ti{sub 0.5}O{sub 5} show iso-structural phase transition above 12 GPa similar to the one observed in undoped BiMn{sub 2}O{sub 5}; however anisotropic compressional behavior is found to be more enhanced in the doped case. Unlike undoped system, an anomalous lattice expansion along c axis has been observed in BiMn{sub 1.5}Ti{sub 0.5}O{sub 5} above 12 GPa; whereas the b lattice parameter has been found to be more compressible as compared to BiMn{sub 2}O{sub 5}. As doping with Ti reduces the magnetic interactions among Mn ions, the observed changes are suggestive of having adverse magnetic implications in the observed iso-structural phase transition.

  11. Rapid liquid phase sintered Mn doped BiFeO{sub 3} ceramics with enhanced polarization and weak magnetization

    SciTech Connect (OSTI)

    Kumar, Manoj; Yadav, K. L. [Smart Material Research Laboratory, Department of Physics, Indian Institute of Technology, Roorkee-247667 (India)

    2007-12-10T23:59:59.000Z

    Single-phase BiFe{sub 1-x}Mn{sub x}O{sub 3} multiferroic ceramics have been synthesized by rapid liquid phase sintering method to study the influence of Mn substitution on their crystal structure, dielectric, magnetic, and ferroelectric behaviors. From XRD analysis it is seen that Mn substitution does not affect the crystal structure of the BiFe{sub 1-x}Mn{sub x}O{sub 3} system. An enhancement in magnetization was observed for BiFe{sub 1-x}Mn{sub x}O{sub 3} ceramics. However, the ferooelectric hysteresis loops were not really saturated, we observed a spontaneous polarization of 10.23 {mu}C/cm{sup 2} under the applied field of 42 kV/cm and remanent polarization of 3.99 {mu}C/cm{sup 2} for x=0.3 ceramic.

  12. Growth of single-crystal {alpha}-MnO{sub 2} nanorods on multi-walled carbon nanotubes

    SciTech Connect (OSTI)

    Chen Yong [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Key Laboratory of Tropic Biological Resources, MOE, Hainan University, 58 Renmin Road, Haikou 570228 (China); Liu Chenguang; Liu Chang [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Lu Gaoqing [ARC Centre for Functional Nanomaterials, Australian Institute of Bioengineering and Nanotechnology, University of Queensland, QLD 4072 (Australia); Cheng Huiming [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)], E-mail: cheng@imr.ac.cn

    2007-11-06T23:59:59.000Z

    Single-crystal {alpha}-MnO{sub 2} nanorods were grown on multi-walled carbon nanotubes (MWNTs) in H{sub 2}SO{sub 4} aqueous solution. The morphology and microstructure of the composites were examined by transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffractometry and energy dispersive spectroscopy (EDS). The results show that {alpha}-MnO{sub 2} single-crystal nanorods with a mean diameter of 15 nm were densely grown on the surface of MWNTs. Those MWNTs/MnO{sub 2} composites were used as an electrode material for supercapacitors, and it was found that the supercapacitor performance using MWNTs/MnO{sub 2} composites was improved largely compared to that using pure MWNTs and {alpha}-MnO{sub 2} nanorod mechanically mixed with MWNTs.

  13. Bulk and surface half-metallicity: The case of D0{sub 3}-type Mn{sub 3}Ge

    SciTech Connect (OSTI)

    Liu, Hao; Gao, G. Y., E-mail: guoying-gao@mail.hust.edu.cn; Hu, Lei; Ni, Yun; Zu, Fengxia; Zhu, Sicong; Wang, Shuling; Yao, K. L. [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-01-21T23:59:59.000Z

    Motivated by the experimental realization of D0{sub 22}-type Mn{sub 3}Ge (001) films [Kurt et al. Appl. Phys. Lett. 101, 132410 (2012)] and the structural stability of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge [Zhang et al. J. Phys.: Condens. Matter 25, 206006 (2013)], we use the first-principles calculations based on the full potential linearized augmented plane-wave method to investigate the electronic and magnetic properties of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge and its (001) surface. We show that bulk D0{sub 3}-Mn{sub 3}Ge is a half-metallic ferromagnet with the minority-spin energy gap of 0.52?eV and the magnetic moment of 1.00??{sub B} per formula unit. The bulk half-metallicity is preserved at the pure Mn-terminated (001) surface due to the large exchange split, but the MnGe-terminated (001) surface destroys the bulk half-metallicity. We also reveal that the surface stabilities are comparable between the D0{sub 3}-Mn{sub 3}Ge (001) and the experimental D0{sub 22}-Mn{sub 3}Ge (001), which indicates the feasibility to grow the Mn{sub 3}Ge (001) films with D0{sub 3} phase other than D0{sub 22} one. The surface half-metallicity and stability make D0{sub 3}-Mn{sub 3}Ge a promising candidate for spintronic applications.

  14. Redox Exchange Induced MnO2 Nanoparticle Enrichment in Poly(3,4-ethylenedioxythiophene) Nanowires for Electrochemical Energy Storage

    SciTech Connect (OSTI)

    Liu, R; Duay, Jonathon; Lee, Sang Bok

    2010-01-01T23:59:59.000Z

    MnO{sub 2} nanoparticle enriched poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires are fabricated by simply soaking the PEDOT nanowires in potassium permanganate (KMnO{sub 4}) solution. The structures of these MnO{sub 2} nanoparticle enriched PEDOT nanowires are characterized by SEM and TEM, which show that the MnO{sub 2} nanoparticles have uniform sizes and are finely dispersed in the PEDOT matrix. The chemical constituents and bonding of these composite nanowires are characterized by energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, which indicate that the formation and dispersion of these MnO{sub 2} nanoparticles into the nanoscale pores of the PEDOT nanowires are most likely triggered by the reduction of KMnO{sub 4} via the redox exchange of permanganate ions with the functional group on PEDOT. Varying the concentrations of KMnO{sub 4} and the reaction time controls the loading amount and size of the MnO{sub 2} nanoparticles. Cyclic voltammetry and galvanostatic charge?discharge are used to characterize the electrochemical properties of these MnO{sub 2} nanoparticle loaded PEDOT nanowires. Due to their extremely high exposed surface area with nanosizes, the pristine MnO{sub 2} nanoparticles in these MnO{sub 2} nanoparticle enriched PEDOT nanowires show very high specific capacitance (410 F/g) as the supercapacitor electrode materials as well as high Li+ storage capacity (300 mAh/g) as cathode materials of Li ion battery, which boost the energy storage capacity of PEDOT nanowires to 4 times without causing excessive volume expansion in the polymer. The highly conductive and porous PEDOT matrix facilitates fast charge/discharge of the MnO{sub 2} nanoparticles and prevents them from agglomerating. These synergic properties enable the MnO{sub 2} nanoparticle enriched PEDOT nanowires to be promising electrode materials for supercapacitors and lithium ion batteries.

  15. Mixing Rocksalt and Wurtzite Structure Binary Nitrides to Form Novel Ternary Alloys: ScGaN and MnGaN

    E-Print Network [OSTI]

    Mixing Rocksalt and Wurtzite Structure Binary Nitrides to Form Novel Ternary Alloys: ScGaN and Mn wurtzite structure and tetrahedral bonding, both MnN and ScN are face-centered tetragonal (fct [11]. Though challenging, growth of wurtzite MnGaN alloy by molecular beam epitaxy using radio

  16. FeMn/Fe/Co/Cu(1,1,10) films studied using the magneto-optic Kerr effect and photoemission electron microscopy

    E-Print Network [OSTI]

    Meng, Y.

    2012-01-01T23:59:59.000Z

    B 84, 064416 (2011) FeMn/Fe/Co/Cu(1,1,10) ?lms studied usingmeasurements on FeMn/ Fe(8ML)/Co/vicinal Cu(001), in whichthe FeMn(10ML)/Fe(2ML)/Co(20ML)/Cu(1,1,10) sample growth. (

  17. Suppression of g phase in Ni38Co12Mn41Sn9 alloy by melt spinning and its effect on martensitic transformation and magnetic properties

    E-Print Network [OSTI]

    Zheng, Yufeng

    Ni43Co7Mn39Sn11 alloy fabricated by spark plasma sintering (SPS) [3]. In NiMnSn, NiMnGa and Ni by spark plasma sintering [3]. The g phase usually deteriorates shape memory effect due to its impediment

  18. mn header will be provided by the publisher Linear Passive Stationary Scattering Systems

    E-Print Network [OSTI]

    Rovnyak, James

    mn header will be provided by the publisher Linear Passive Stationary Scattering Systems 26, Odessa 65020, Ukraine 2 Department of Mathematics, University of Virginia, P. O. Box 400137@farlep.net Corresponding author: e-mail: rovnyak@Virginia.edu e-mail: sergey saprikin@ukr.net Copyright line

  19. Electrical gating effects on the magnetic properties of (Ga,Mn)As diluted magnetic semiconductors

    E-Print Network [OSTI]

    Owen, Man Hon Samuel

    2010-11-16T23:59:59.000Z

    -effect transistor (FET) based on low-doped Ga0.975Mn0.025As was fabricated. It has an in-built n-GaAs back-gate, which, in addition to being a normal gate, enhances the gating effects, especially in the depletion of the epilayer, by decreasing the effective channel...

  20. Electrodeposition of Mn-Co Alloys on Stainless Steels for SOFC Interconnect Application

    SciTech Connect (OSTI)

    Wu, J. (West Virginia University); Jiang, Y. (West Virginia University); Johnson, C.; Gong, M. (West Virginia University); Liu, X. (West Virginia University)

    2007-09-01T23:59:59.000Z

    Chromium-containing ferritic stainless steels are the most popular materials for solid oxide fuel cell (SOFC) interconnect applications because of its oxidation resistance and easy fabrication process. However, excessive scale growth and chromium evaporation will degrade the cell performance. Highly conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. Mn1.5Co1.5O4 spinel is one of the most promising coatings for interconnect application because of its high conducitivy, good chromium retention capability, as well as good CTE match. Electroplating of alloys or thin film multilayers followed by controlled oxidation to the desired spinel phase offers an additional deposition option. In the present study binary Mn/Co alloys was fabricated by electrodeposition, and polarization curves were used to characterize the cathodic reactions on substrate surface. By controlling the current density precisely, coatings with Mn/Co around 1:1 has been successfully deposited in Mn/Co =10 solutions, SEM and EDX was used to characterize the surface morphology and composition.

  1. Thermoelectric properties of high quality nanostructured Ge:Mn thin D. Tanoff2*

    E-Print Network [OSTI]

    Boyer, Edmond

    Thermoelectric properties of high quality nanostructured Ge:Mn thin films D. Taïnoff2* , A. Barski2 nanostructured thin films and the measurement of their thermoelectric properties. We investigate the growth of Ge temperature thermoelectric properties of these layers containing spherical inclusions are discussed regarding

  2. Chobert MN et al LIVER PRECURSOR CELLS INCREASE HEPATIC FIBROSIS INDUCED BY CHRONIC

    E-Print Network [OSTI]

    Boyer, Edmond

    by chronic carbon tetrachloride (CCl4) administration for 6 weeks, in combination with chronic; CCl4, carbon tetrachloride; CK19, cytokeratin 19; CCR2, chemokine C-C motif receptor 2; EMTChobert MN et al LIVER PRECURSOR CELLS INCREASE HEPATIC FIBROSIS INDUCED BY CHRONIC CARBON

  3. Mn-Substituted Inorganic-Organic Hybrid Materials Based on ZnSe

    E-Print Network [OSTI]

    Li, Jing

    for optoelectronics and information storage technology. In this study, we demonstrate that the hybrid nanostructuresMn-Substituted Inorganic-Organic Hybrid Materials Based on ZnSe: Nanostructures That May Lead are highly desirable and extremely attractive in the development of new multifunctional devices

  4. Frustration and multiferroic behavior in Ca3CoMnO6

    SciTech Connect (OSTI)

    Zapf, Vivien [Los Alamos National Laboratory

    2012-06-01T23:59:59.000Z

    Lu{sub 2}MnCoO{sub 6} and Ca{sub 3}MnCoO{sub 6} satisfy one of the primary goals of multiferroics research, namely ferromagnetic-like magnetization coupled to ferroelectric-like polarization. Thus the mechanism for magnetoelectric coupling in these materials deserves careful study. New data shows that the physics of these compound may be related to the classic 'ANNNI' model. Frustration between ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions between Ising spins creates an 'up up down down' magnetic structure in zero magnetic field, along c-axis chains that consist of alternating Co and Mn ions. In applied magnetic fields 'up up down,' 'up up up down' and other metastable variations can evolve, yielding hysteretic ferromagnetic-like magnetization. The key is that the phase slips between regions of 'up' and 'down' carries an electric polarization due to broken spatial inversion symmetry. Thus these phase slips can be manipulated with both electric and magnetic fields. The result is a profusion of magnetic and electric states that are closely-spaced in temperature, electric, and magnetic field. We present experimental studies of the magnetic, electric, and structural properties of these two compounds. We include very new data up to 100 Ton Ca{sub 3}CoMnO{sub 6} that resolves a key controversy of over the magnetic structure and the size of the moments.

  5. Solar DEM Model Proposal : A solar image in color band b, mn pixels,

    E-Print Network [OSTI]

    Wolfe, Patrick J.

    Solar DEM Model Proposal : A solar image in color band b, m×n pixels, containing a particular solar 11 )( #12;Solar DEM Model Proposal : the volume (abundance?) of ion ii : the proportion of the total volume at temperature t t T t bitt I i ib MIE 11 )( #12;Solar Dataset · 15 Filters.txt files

  6. Modulation on Ni{sub 2}MnGa(001) surface

    SciTech Connect (OSTI)

    D'Souza, S. W.; Rai, Abhishek; Nayak, J.; Maniraj, M.; Dhaka, R. S.; Barman, S. R.; Schlagel, D. L.; Lograsso, T. A. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore, 452001, Madhya Pradesh (India); Ames Laboratory U. S. DOE, Iowa State University, Ames, Iowa 50011-3020 (United States)

    2011-07-15T23:59:59.000Z

    We report periodic modulation on (001) surface of Ni2MnGa ferromagnetic shape memory alloy. For the stoichiometric surface, analysis of the low energy electron diffraction (LEED) spot profiles shows that the modulation is incommensurate. The modulation appears at 200 K, concomitant with the first order structural transition to the martensitic phase.

  7. Mixed Zn and O substitution of Co and Mn in ZnO

    E-Print Network [OSTI]

    Pereira, Lino Miguel da Costa; Decoster, Stefan; Correia, João Guilherme; Amorim, Lígia Marina; da Silva, Manuel Ribeiro; Araújo, João Pedro; Vantomme, André

    2011-01-01T23:59:59.000Z

    The physical properties of an impurity atom in a semiconductor are primarily determined by the lattice site it occupies. In general, this occupancy can be correctly predicted based on chemical intuition, but not always. We report on one such exception in the dilute magnetic semiconductors Co- and Mn-doped ZnO, experimentally determining the lattice location of Co and Mn using ??-emission channeling from the decay of radioactive 61Co and 56Mn implanted at the ISOLDE facility at CERN. Surprisingly, in addition to the majority substituting for Zn, we find up to 18% (27%) of the Co (Mn) atoms in O sites, which is virtually unaffected by thermal annealing up to 900 °C. We discuss how this anion site configuration, which had never been considered before for any transition metal in any metal oxide material, may in fact have a low formation energy. This suggests a change in paradigm regarding transition-metal incorporation in ZnO and possibly other oxides and wide-gap semiconductors.

  8. Shapes of Knotted Cyclic Polymers Eric J. Rawdon, University of St. Thomas, Saint Paul, MN, USA

    E-Print Network [OSTI]

    Bigelow, Stephen

    Shapes of Knotted Cyclic Polymers Eric J. Rawdon, University of St. Thomas, Saint Paul, MN, USA, USA Momentary configurations of long polymers at thermal equilibrium usually deviate from spherical of asphericity (or prolateness) that describe these momentary ellipsoidal shapes of a polymer are determined

  9. Microscopic mechanism of the noncrystalline anisotropic magnetoresistance in (Ga,Mn)As

    E-Print Network [OSTI]

    Vyborny, Karel; Kucera, Jan; Sinova, Jairo; Rushforth, A. W.; Gallagher, B. L.; Jungwirth, T.

    2009-01-01T23:59:59.000Z

    Starting with a microscopic model based on the Kohn-Luttinger Hamiltonian and kinetic p-d exchange combined with Boltzmann formula for conductivity we identify the scattering from magnetic Mn combined with the strong spin-orbit interaction of the Ga...

  10. Reduced-activation austenitic stainless steels: The Fe--Mn--Cr--C system

    SciTech Connect (OSTI)

    Klueh, R.L.; Maziasz, P.J.

    1988-01-01T23:59:59.000Z

    Nickel-free manganese-stabilized steels are being developed for fusion-reactor applications. As the first part of this effort, the austenite-stable region in the Fe--Mn--Cr--C system was determined. Results indicated that the Schaeffler diagram developed for Fe--Ni--Cr--C alloys cannot be used to predict the constituents expected for high-manganese steels. This is true because manganese is not as strong an austenite stabilizer relative to delta-ferrite formation as predicted by the diagram, but it is a stronger austenite stabilizer relative to martensite than predicted. Therefore, the austenite-stable region for Ne--Mn--Cr--C alloys occurs at lower chromium and hugher combinations of manganese and carbon than predicted by the Schaeffler diagram. Development of a manganese-stabilized stainless steel should be possible in the composition range of 20 to 25% Mn, 10 to 15% Cr, and 0.01 to 0.25%C. Tensile behavior of an Fe--20%Mn--12%Cr--0.25%C alloy was determined. The strength and ductility of this possible base composition was comparable to type 316 stainless steel in both the solution-annealed and cold-worked condition.

  11. Single Nanorod Devices for Battery Diagnostics: A Case Study on LiMn2O4

    E-Print Network [OSTI]

    Cui, Yi

    nanostructure devices as a powerful new diagnostic tool for batteries with LiMn2O4 nanorod materials energy storage devices for portable electronic devices, power tools, and electrical vehicles.1-4 Anodes applied to battery researches. This work represents the first example of single nanostructure device

  12. A violet emission in ZnS:Mn,Eu: Luminescence and applications for radiation detection

    SciTech Connect (OSTI)

    Ma, Lun; Chen, Wei, E-mail: weichen@uta.edu [Department of Physics and the SAVANT Center, The University of Texas at Arlington, Arlington, Texas 76019-0059 (United States); Jiang, Ke [Center for Biofrontiers Institute, University of Colorado at Colorado Springs, 1420 Austin Bluffs Pkwy., Colorado Springs, Colorado 80918 (United States); Liu, Xiao-tang [Department of Physics and the SAVANT Center, The University of Texas at Arlington, Arlington, Texas 76019-0059 (United States); Department of Applied Chemistry, College of Science, South China Agricultural University, Guangzhou 510642 (China)

    2014-03-14T23:59:59.000Z

    We prepared manganese and europium co-doped zinc sulfide (ZnS:Mn,Eu) phosphors and used them for radiation detection. In addition to the red fluorescence at 583?nm due to the d-d transition of Mn ions, an intense violet emission at 420?nm is newly observed in ZnS:Mn,Eu phosphors. The emission is related to Eu{sup 2+} doping but only appears at certain Eu{sup 2+} concentrations. It is found that the intensity of the 420?nm violet fluorescence is X-ray does-dependent, while the red fluorescence of 583?nm is not. The ratio of fluorescence intensities at 420?nm and 583?nm has been monitored as a function of X-ray doses that exposed upon the ZnS:Mn,Eu phosphors. Empirical formulas are provided to estimate the doses of applied X-ray irradiation. Finally, possible mechanisms of X-ray irradiation induced fluorescence quenching are discussed. The intense 420?nm emission not only provides a violet light for solid state lighting but also offers a very sensitive method for radiation detection.

  13. Helical antiferromagnetic ordering in Lu1-xScxMnSi

    SciTech Connect (OSTI)

    Goetsch, Ryan J [Ames Laboratory; Anand, V K [Ames Laboratory; Johnston, David C [Ames Laboratory

    2014-08-01T23:59:59.000Z

    Polycrystalline samples of Lu1?xScxMnSi (x=0, 0.25, 0.5) are studied using powder x-ray diffraction, heat capacity Cp, magnetization, magnetic susceptibility ?, and electrical resistivity ? measurements versus temperature T and magnetic field H. This system crystallizes in the primitive orthorhombic TiNiSi-type structure (space group Pnma) as previously reported. The ?(T) data indicate metallic behavior. The Cp(T), ?(T), and ?(T) measurements consistently indicate long-range antiferromagnetic (AF) transitions with AF ordering temperatures TN=246, 215, and 188 K for x=0, 0.25, and 0.5, respectively. A second transition is observed at somewhat lower T for each sample from the ?(T) and ?(T) measurements, which we speculate are due to spin reorientation transitions; these second transitions are completely suppressed in H=5.5 T. The Cp data below 10 K for each composition indicate an enhanced Sommerfeld electronic heat capacity coefficient for the series in the range ?=24–29 mJ/mol K2. The ?(T) measurements up to 1000 K were fitted by local-moment Curie-Weiss behaviors which indicate a low Mn spin S?1. The ? data below TN are analyzed using the Weiss molecular field theory for a planar noncollinear cycloidal AF structure with a composition-dependent pitch, following the previous neutron diffraction work of Venturini et al. [J. Alloys Compd. 256, 65 (1997)]. Within this model, the fits indicate a turn angle between Mn ordered moments along the cycloid axis of ?100? or ?145?, either of which indicate dominant AF interactions between the Mn spins in the Lu1?xScxMnSi series of compounds.

  14. Enhanced magnetic and electrical properties in amorphous Ge:Mn thin films by non-magnetic codoping

    SciTech Connect (OSTI)

    Yin Wenjing; Kell, Copeland D.; Duska, Chris; Lu Jiwei; Floro, Jerrold A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); He Li; Hull, Robert [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Dolph, Melissa C. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Wolf, Stuart A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2012-02-01T23:59:59.000Z

    Amorphous Ge{sub 1-x}Mn{sub x} thin films have been prepared by co-depositing Ge and Mn on SiO{sub 2}/Si using an ultrahigh vacuum molecular beam epitaxy system. Across a range of growth temperatures and Mn concentrations (2.8 at. %, 10.9 at. %, and 21.3 at. %), we achieved enhanced magnetic and electrical properties with non-magnetic codopants dispersed in the films. Self-assembled Mn-rich amorphous nanostructures were observed in the amorphous Ge matrix, either as isolated nanoclusters or as nanocolumns, depending on Mn concentration. The ferromagnetic saturation moments were found to increase with Mn concentration and reached a maximum of 0.7 {mu}{sub B}/Mn in the as-grown samples. Two magnetic transition temperatures around 15 K and 200 K were observed in these amorphous MBE-grown samples. Coercivity is considered within the context of local magnetic anisotropy. The anomalous Hall effect confirmed a strong correlation between the magnetization and transport properties, indicating that global ferromagnetic coupling was carrier-mediated rather than through direct exchange. In addition, negative magnetoresistance was detected from 5 K to room temperature.

  15. High-field electroluminescence in semiconductor tunnel junctions with a Mn-doped GaAs layer

    SciTech Connect (OSTI)

    Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-0033 (Japan); Yatsui, Takashi; Ohtsu, Motoichi; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nanophotonics Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-09-21T23:59:59.000Z

    We investigated high-field electroluminescence (EL) in semiconductor tunnel junctions with a Mn-doped GaAs layer (here, referred to as GaAs:Mn). Besides the band-gap emission of GaAs, the EL spectra show visible light emissions with two peaks at 1.94?eV and 2.19?eV, which are caused by d-d transitions of the Mn atoms excited by hot electrons. The threshold voltages for band-gap and visible light EL in the tunnel junctions with a GaAs:Mn electrode are 1.3?V higher than those of GaAs:Mn excited by hot holes in reserve biased p{sup +}-n junctions, which is consistent with the hot carrier transport in the band profiles of these structures. Our EL results at room temperature show that the electron temperature in GaAs:Mn can be as high as ?700?K for a low input electrical power density of 0.4?W/cm{sup 2}, while the lattice temperature of the GaAs:Mn layer can be kept at 340?K.

  16. Structural and magnetic properties of magnetron sputtered Ni-Mn-Sn ferromagnetic shape memory alloy thin films

    SciTech Connect (OSTI)

    Vishnoi, Ritu; Kaur, Davinder [Functional Nanomaterials Research Laboratory, Department of Physics and Center of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2010-05-15T23:59:59.000Z

    In the present study, structural and magnetic properties of Mn-rich, off-stoichiometric, nanocrystalline Ni-Mn-Sn ferromagnetic shape memory alloy thin films, grown on Si (100) substrates at 550 deg. C by dc magnetron sputtering have been systematically investigated. The crystallization, surface morphology, and structural features were studied using x-ray diffraction, atomic force microscopy, and field emission scanning electron microscopy. The structural transition from austenite to martensite was observed with an increase of Mn content. Austenitic phase with mixed L2{sub 1}/A2+B2 structure has been observed at room temperature in Ni{sub 52.6}Mn{sub 23.7}Sn{sub 23.6} (S{sub 1}) and Ni{sub 51.5}Mn{sub 26.1}Sn{sub 22.2} (S{sub 2}) films, while those with composition of Ni{sub 58.9}Mn{sub 28.0}Sn{sub 13.0} (S{sub 3}) and Ni{sub 58.3}Mn{sub 29.0}Sn{sub 12.6} (S{sub 4}) show martensitic phase with 14M modulated monoclinic structures. Field induced martensite-austenite transformation has been observed in magnetization studies using superconducting quantum interference device magnetometer. Temperature dependent magnetization measurements demonstrate the influence of magnetic field on the structural phase transition temperature. The investigations reveal an increase of martensitic transformation temperature (T{sub M}) with corresponding increase in substitution of Mn. The films exhibit ferromagnetic behavior at low temperatures below Curie temperature (T{sub C}). The decrease in saturation moment with increasing Mn content, indicates the existence of antiferromagnetic correlations within ferromagnetic matrix.

  17. Atomic moments in Mn2CoAl thin films analyzed by X-ray magnetic circular dichroism

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jamer, M. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics; Sterbinsky, G. [Brookhaven National Laboratory (BNL), Upton, NY (United States). Photon Sciences Directorate; Assaf, B. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics; Arena, D. [Brookhaven National Laboratory (BNL), Upton, NY (United States). Photon Sciences Directorate; Heiman, D. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics

    2014-12-07T23:59:59.000Z

    Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn2CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. The results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value. (auth)

  18. Precipitation in cold-rolled Al–Sc–Zr and Al–Mn–Sc–Zr alloys prepared by powder metallurgy

    SciTech Connect (OSTI)

    Vlach, M., E-mail: martin.vlach@mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16 Prague (Czech Republic); Stulikova, I.; Smola, B.; Kekule, T.; Kudrnova, H.; Danis, S. [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16 Prague (Czech Republic); Gemma, R. [King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, 23955-6900 Thuwal (Saudi Arabia); Ocenasek, V. [SVÚM a.s., Podnikatelská 565, CZ-190 11 Prague (Czech Republic); Malek, J. [Czech Technical University in Prague, Faculty of Mechanical Engineering, CZ-120 00 Prague (Czech Republic); Tanprayoon, D.; Neubert, V. [Institut für Materialprüfung und Werkstofftechnik, Freiberger Strasse 1, D-38678 Clausthal-Zellerfeld (Germany)

    2013-12-15T23:59:59.000Z

    The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 °C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles precipitated during extrusion at 350 °C in the alloys studied. Additional precipitation of the Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 °C. The precipitation of the Al{sub 6}Mn- and/or Al{sub 6}(Mn,Fe) particles of a size ? 1.0 ?m at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 °C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al{sub 3}Sc particles formation and/or coarsening and that of the Al{sub 6}Mn and/or Al{sub 6}(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al{sub 3}Sc-phase and the Al{sub 6}Mn-phase precipitation. - Highlights: • The Mn, Sc and Zr additions to Al totally suppresses recrystallization at 550 °C. • The Sc,Zr-containing particle precipitation is slightly facilitated by cold rolling. • The Mn-containing particle precipitation is highly enhanced by cold rolling. • Cold rolling has no effect on activation energy of the Al{sub 3}Sc and Al{sub 6}Mn precipitation. • The texture development is affected by high solid solution strengthening by Mn.

  19. Penetration depth and absorption mechanisms of spin currents in Ir{sub 20}Mn{sub 80} and Fe{sub 50}Mn{sub 50} polycrystalline films by ferromagnetic resonance and spin pumping

    SciTech Connect (OSTI)

    Merodio, P.; Ghosh, A.; Lemonias, C.; Gautier, E.; Ebels, U.; Chshiev, M.; Béa, H., E-mail: vincent.baltz@cea.fr, E-mail: helene.bea@cea.fr; Baltz, V., E-mail: vincent.baltz@cea.fr, E-mail: helene.bea@cea.fr [SPINTEC, UMR 8191 CNRS/INAC-CEA/UJF-Grenoble 1/Grenoble-INP, F-38054 Cedex (France); Bailey, W. E., E-mail: web54@columbia.edu [Mat. Sci. and Engn. Program, Department of Appl. Phys. and Appl. Math., Columbia University, New York, New York 10027 (United States)

    2014-01-20T23:59:59.000Z

    Spintronics relies on the spin dependent transport properties of ferromagnets (Fs). Although antiferromagnets (AFs) are used for their magnetic properties only, some fundamental F-spintronics phenomena like spin transfer torque, domain wall motion, and tunnel anisotropic magnetoresistance also occur with AFs, thus making AF-spintronics attractive. Here, room temperature critical depths and absorption mechanisms of spin currents in Ir{sub 20}Mn{sub 80} and Fe{sub 50}Mn{sub 50} are determined by F-resonance and spin pumping. In particular, we find room temperature critical depths originating from different absorption mechanisms: dephasing for Ir{sub 20}Mn{sub 80} and spin flipping for Fe{sub 50}Mn{sub 50}.

  20. Mn concentration dependent structural and optical properties of a-plane Zn{sub 0.99-x}Mn{sub x}Na{sub 0.01}O

    SciTech Connect (OSTI)

    Lu, B., E-mail: binlu@zju.edu.cn; Zhou, T. T.; Ma, M. J.; Ye, Y. H.; Ye, Z. Z.; Lu, J. G.; Pan, X. H. [State Key Laboratory of Silicon Materials, Cyrus Tang Center for Sensor Materials and Applications, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2013-12-14T23:59:59.000Z

    Non-polar a-plane (112{sup ¯}0) Zn{sub 0.99?x}Mn{sub x}Na{sub 0.01}O (x?=?0, 0.02, 0.03, 0.04, and 0.05) thin films have been prepared on r-plane (112{sup ¯}0) sapphire substrates by pulsed laser deposition (PLD). The influences of Mn content on the structural and optical properties of the films have been studied. It is indicated that moderate Mn doping facilitates the non-polar growth of ZnO, and all the doped films are single phase with a hexagonal wurtzite structure. The transmittance spectra suggested that all films are transparent in the visible region exhibiting a transmittance above 80%. Mn{sup 2+} doped Zn{sub 0.99}Na{sub 0.01}O shows an initial decrease of optical band gap (OBG) for small concentration of Mn, followed by a monotonic increase. The anomalous decrease in OBG for low concentrations of Mn is attributed to the strong exchange interaction present between the sp electrons of the host matrix and d electrons of Mn. Emission studies were also performed showing suppressed blue-shifted ultraviolet band and dominant violet-blue bands, which might originate from the zinc vacancy (V{sub Zn}) and zinc interstitial (Zn{sub i}) defects. The intensity of defect-related emission peaks is Mn doping-level-dependent as well and the results coincide well with that from the structural analyses.

  1. Electronic structure of the molecule-based magnet MnN,,CN...22 from theory and experiment

    E-Print Network [OSTI]

    Liu, Amy Y.

    of SmCo5 and Nd2Fe14B2.2 For Mn N(CN)2 2, Kurmoo et al.2 report that the structure be- haves as a canted

  2. Synthesis and Lithiation Mechanisms of Dirutile and Rutile LiMnF4: Two New Conversion Cathode Materials

    E-Print Network [OSTI]

    Twu, Nancy H.

    Driven by the need for new cathode battery materials with high energy density, fluorides have emerged as promising candidates due to their high voltages. From high throughput computations, dirutile LiMnF4 was identified ...

  3. Growth optimization and structural analysis for ferromagnetic Mn-doped ZnO layers deposited by radio frequency magnetron sputtering

    SciTech Connect (OSTI)

    Abouzaid, M.; Ruterana, P.; Liu, C.; Morkoc, H. [SIFCOM UMR 6176 CNRS-ENSICAEN, 6 Boulevard du Marechal Juin, 14050 Caen Cedex (France); Department of Electrical Engineering, Virginia Commonwealth University, Richmond Virginia 23284 (United States)

    2006-06-01T23:59:59.000Z

    The effect of the deposition temperature on the crystalline quality of (Zn,Mn)O is investigated in thin films prepared by radio frequency magnetron sputtering on c-plane sapphire and GaN substrates. The layers are made of a 0.5 {mu}m Mn-doped layer towards the surface on top of a 150 nm pure ZnO buffer. Depending on the deposition temperature, the layers can exhibit a columnar structure; the adjacent domains are rotated from one another by 90 deg. , putting [1010] and [1120] directions face to face. At high Mn concentration the columnar structure is blurred by the formation of Mn rich precipitates. Only one variety of domains is observed at an optimal deposition temperature of 500 deg. C: they are slightly rotated around the [0001] axis (mosaic growth) and bounded by threading dislocations.

  4. Chemical synthesis of crystalline, pure or Mn-doped ZnGa2O4 powders at 90 C

    E-Print Network [OSTI]

    Tas, A. Cuneyt

    in a constant-temperature laboratory oven. Single-phase pure or Mn-doped zinc gallate powders synthesized-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, inductively-coupled plasma

  5. Heat capacity of the site-diluted spin dimer system Ba?(Mn1-xVx)?O?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

    2011-08-01T23:59:59.000Z

    Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba?(Mn1-xVx)?O?. The parent compound Ba?Mn?O? is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d² Mn?? ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d? V?? ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0?x?0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for a phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.

  6. Anti-site disorder and improved functionality of Mn?NiX (X = Al, Ga, In, Sn) inverse Heusler alloys

    SciTech Connect (OSTI)

    Paul, Souvik; Kundu, Ashis; Ghosh, Subhradip, E-mail: subhra@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Sanyal, Biplab [Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala (Sweden)

    2014-10-07T23:59:59.000Z

    Recent first-principles calculations have predicted Mn?NiX (X = Al, Ga, In, Sn) alloys to be magnetic shape memory alloys. Moreover, experiments on Mn?NiGa and Mn?NiSn suggest that the alloys deviate from the perfect inverse Heusler arrangement and that there is chemical disorder at the sublattices with tetrahedral symmetry. In this work, we investigate the effects of such chemical disorder on phase stabilities and magnetic properties using first-principles electronic structure methods. We find that except Mn?NiAl, all other alloys show signatures of martensitic transformations in presence of anti-site disorder at the sublattices with tetrahedral symmetry. This improves the possibilities of realizing martensitic transformations at relatively low fields and the possibilities of obtaining significantly large inverse magneto-caloric effects, in comparison to perfect inverse Heusler arrangement of atoms. We analyze the origin of such improvements in functional properties by investigating electronic structures and magnetic exchange interactions.

  7. The Design and Feasibility of a 10 mN Chemical Space Propulsion Alexander Bruccoleri , Paulo Lozano

    E-Print Network [OSTI]

    , Paulo Lozano June 2009 SSL # 3-09 #12;#12;The Design and Feasibility of a 10 mN Chemical Space Propulsion Thruster Alexander Bruccoleri , Paulo Lozano June 2009 SSL # 3-09 This work is based

  8. Nmr Study of Thiocarbonyl Derivatives of Fe and Mn were made with solutions of the tungsten and molybdenum species

    E-Print Network [OSTI]

    Bodner, George M.

    Nmr Study of Thiocarbonyl Derivatives of Fe and Mn were made with solutions of the tungsten.g.. the tungsten ion readily oxidizes in aqueous acid [A. Samotus and B. Kosowicz-Czajkowska, Rocz. Chem., 45, 1623

  9. Coulomb interaction of acceptors in Cd{sub 1?x}Mn{sub x}Te/CdTe quantum dot

    SciTech Connect (OSTI)

    Kalpana, P.; Nithiananthi, P., E-mail: kjkumar-gri@rediffmail.com; Jayakumar, K., E-mail: kjkumar-gri@rediffmail.com [Department of Physics, Gandhigram Rural University, Gandhigram-624302, TamilNadu (India); Reuben, A. Merwyn Jasper D. [Department of Physics, School of Engineering, Saveetha University, Thandalam, Chennai- 600104, TamilNadu (India)

    2014-04-24T23:59:59.000Z

    The investigation on the effect of confining potential like isotropic harmonic oscillator type potential on the binding and the Coulomb interaction energy of the double acceptors in the presence of magnetic field in a Cd{sub 1?x}Mn{sub x}Te/CdTe Spherical Quantum Dot has been made for the Mn ion composition x=0.3 and compared with the results obtained from the square well type potential using variational procedure in the effective mass approximation.

  10. Spectroscopic and magnetic properties of Mn doped GaN epitaxial films grown by plasma assisted molecular beam epitaxy

    SciTech Connect (OSTI)

    Vidyasagar, R., E-mail: dr.vidyasagar1979@gmail.com [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China); Lin, Y.-T.; Tu, L.-W. [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China)] [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China)

    2012-12-15T23:59:59.000Z

    Graphical abstract: We report here that micro-Raman scattering spectrum for Mn doped GaN thin film has displayed a new peak manifested at 578 cm{sup ?1}, by which it is attributed to interior LVM originated by the incorporation of Mn ions in place of Ga sites. Mn doped GaN thin film also showed the typical negative magnetoresistance up to ?50 K, revealing that the film showed magnetic ordering of spins below 50 K. Display Omitted Highlights: ? GaN and Mn doped GaN single phase wurtzite structures grown by PAMBE. ? The phase purity of the epilayers investigated by HRXRD, HRSEM and EDX. ? The red shift in near band edge emission has been observed using micro-PL. ? A new peak related LVM at 578 cm{sup ?1} in micro-Raman scattering measurements confirmed Mn doped into GaN. ? Negative-magnetoresistance investigations have showed that the film has T{sub c} < 50 K. -- Abstract: Spectroscopic and magnetic properties of Mn doped GaN, and GaN epitaxial films have been investigated by employing micro-photoluminescence, micro-Raman, and temperature dependent magneto-resistance measurements. The HR-XRD profiles have shown that the epitaxial films are in hexagonal wurtzite structures. Morphology and composition of the films have been examined by field emission scanning electron microscopy, and energy-dispersive X-ray analysis. Micro-photoluminescence spectrum displayed a dominant near band edge emission at 362 nm, which is assigned to near band edge transition within the hexagonal structure of GaN. Raman scattering profiles showed a new vibrational mode at 578 cm{sup ?1}, which is attributed to the vacancy-related local vibrational mode of Mn occupying the Ga site. Temperature dependent negative magnetoresistance measurements provide a direct evidence of magnetic ordering below 50 K for the Mn doped GaN thin film.

  11. Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors

    E-Print Network [OSTI]

    Jungwirth, T.; Wang, KY; Masek, J.; Edmonds, KW; Konig, J.; Sinova, Jairo; Polini, M.; Goncharuk, NA; MacDonald, AH; Sawicki, M.; Rushforth, AW; Campion, RP; Zhao, LX; Foxon, CT; Gallagher, BL.

    2005-01-01T23:59:59.000Z

    . DOI: 10.1103/PhysRevB.72.165204 PACS number#1;s#2;: 75.50.Pp, 75.30.Gw, 73.61.Ey I. INTRODUCTION After some frustration in the community caused by the difficulties encountered in overcoming the apparent Curie temperature limit in #1;Ga,Mn#2;As...Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors T. Jungwirth,1,2 K. Y. Wang,2 J. Ma?ek,3 K. W. Edmonds,2 J?rgen K?nig, 4 Jairo Sinova,5 M. Polini,6 N. A. Goncharuk,1 A. H. MacDonald,7 M. Sawicki,8 A. W. Rushforth,2 R. P...

  12. Structural, elastic, electronic, magnetic and vibrational properties of CuCoMnGa under pressure

    SciTech Connect (OSTI)

    ?yigör, Ahmet [Central Research and Practice Laboratory (AH?LAB), AhiEvran University, 40100 K?r?ehir (Turkey); U?ur, ?ule [Department of Physics, Faculty of Science, Gazi University, 06500 Ankara (Turkey)

    2014-10-06T23:59:59.000Z

    First principles calculations for the structural, electronic, elastic and phonon properties of the cubic quaternary heusler alloy CuCoMnGa on pressure have been reported by density functional theory (DFT) within generalized gradient approximation (GGA). The calculated values of the elastic constants were used for estimations of the Debye temperatures, the bulk modulus, the shear modulus, the young modulus E, the poisson's ratio ? and the B/G ratio. The elastic constants satisfy all of the mechanical stability criteria. The electronic structures of the ferromagnetic configuration for CuCoMnGa have a metallic character. The estimated magnetic moment per formula unit is 3.76 ?{sub B}. The phonon dispersion is studied using the supercell approach, and the stable nature at 0.2 GPa pressure is observed.

  13. MnBi particles with high energy density made by spark erosion

    SciTech Connect (OSTI)

    Nguyen, Phi-Khanh, E-mail: phi@ucsd.edu; Jin, Sungho [Materials Science and Engineering, University of California, San Diego, La Jolla, California 92093 (United States); Center for Magnetic Recording Research, University of California, San Diego, La Jolla, California 92093 (United States); Berkowitz, Ami E. [Physics Department, University of California, San Diego, La Jolla, California 92093 (United States); Center for Magnetic Recording Research, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-05-07T23:59:59.000Z

    We report on the properties of low-temperature phase (LTP)-MnBi particles produced by the rapid-quenching technique of spark-erosion. The as-prepared powder consists of amorphous, crystalline, and superparamagnetic particles, mostly as porous aggregates. The major fraction of the powder consists of 20–30?nm particles. A short anneal crystallizes the amorphous particles producing a high moment, >90% of theoretical M{sub S}, albeit with H{sub C} of a few kOe. If lightly milled, the agglomerates are broken up to yield H{sub C} of 1?T. These findings are supported by the x-ray diffraction pattern showing broadened peaks of the predominant LTP-MnBi phase. The combination of spark erosion, milling, and annealing has produced randomly oriented particles with (BH){sub MAX}???3.0 MGOe. The particles are expected to show record energy product when aligned along their crystallographic easy axes.

  14. Magneto-optical spectroscopy of ferromagnetic shape-memory Ni-Mn-Ga alloy

    SciTech Connect (OSTI)

    Veis, M., E-mail: veis@karlov.mff.cuni.cz; Beran, L.; Zahradnik, M.; Antos, R. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 12116 Prague (Czech Republic); Straka, L. [Aalto University School of Engineering, PL14200, FIN-00076 Aalto (Finland); Kopecek, J.; Fekete, L.; Heczko, O. [Institute of Physics, ASCR, Na Slovance 2, 182 21 Prague (Czech Republic)

    2014-05-07T23:59:59.000Z

    Magneto-optical properties of single crystal of Ni{sub 50.1}Mn{sub 28.4}Ga{sub 21.5} magnetic shape memory alloy in martensite and austenite phase were systematically studied. Crystal orientation was approximately along (100) planes of parent cubic austenite. At room temperature, the sample was in modulated 10M martensite phase and transformed to cubic austenite at 323?K. Spectral dependence of polar magneto-optical Kerr effect was obtained by generalized magneto-optical ellipsometry with rotating analyzer in the photon energy range from 1.2 to 4?eV, and from room temperature to temperature above the Curie point. The Kerr rotation spectra exhibit prominent features typical for complexes containing Mn atoms. Significant spectral changes during transformation to austenite can be explained by different optical properties caused by changes in density of states near the Fermi energy.

  15. Abundance analysis of SB2 binary stars with HgMn primaries

    E-Print Network [OSTI]

    T. Ryabchikova

    1998-05-06T23:59:59.000Z

    We present a short review of the abundances in the atmospheres of SB2 systems with Mercury-Manganese (HgMn) primaries. Up to now a careful study has been made for both components of 8 out of 17 known SB2 binaries with orbital periods shorter than 100 days and mass ratio ranging from 1.08 to 2.2. For all eight systems we observe a lower Mn abundance in the secondary's atmospheres than in the primary's. Significant difference in the abundances is also found for some peculiar elements such as Ga, Xe, Pt. All secondary stars with effective temperatures less than 10000 K show abundance characteristics typical of the metallic-line stars.

  16. Three very young HgMn stars in the Orion OB1 Association

    E-Print Network [OSTI]

    Vincent M. Woolf; David L. Lambert

    1999-05-18T23:59:59.000Z

    We report the detection of three mercury-manganese stars in the Orion OB1 association. HD 37886 and BD-0 984 are in the approximately 1.7 million year old Orion OB1b. HD 37492 is in the approximately 4.6 million year old Orion OB1c. Orion OB1b is now the youngest cluster with known HgMn star members. This places an observational upper limit on the time scale needed to produce the chemical peculiarities seen in mercury-manganese stars, which should help in the search for the cause or causes of the peculiar abundances in HgMn and other chemically peculiar upper main sequence stars.

  17. Magnetochromic effect in multiferroic R In 1 ? x Mn x O 3 ( R = Tb , Dy)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chen, P.; Holinsworth, B. S.; O'Neal, K. R.; Brinzari, T. V.; Mazumdar, D.; Topping, C. V.; Luo, X.; Cheong, S.-W.; Singleton, J.; McGill, S.; Musfeldt, J. L.

    2015-05-01T23:59:59.000Z

    We combined high field magnetization and magneto-optical spectroscopy to investigate spin-charge coupling in Mn-substituted rare-earth indium oxides of chemical formula RIn??xMnxO? (R=Tb, Dy). The edge states, on-site Mn³?d to d excitations, and rare-earth f-manifold excitations all track the magnetization energy due to dominant Zeeman interactions. The field-induced modifications to the rare-earth excitations are quite large because spin-orbit coupling naturally mixes spin and charge, suggesting that the next logical step in the design strategy should be to bring spin-orbit coupling onto the trigonal bipyramidal chromophore site with a 4 or 5d center.

  18. Preparation and Magnetic Properties of MnBi-based Hard/Soft Composite Magnets

    SciTech Connect (OSTI)

    Ma, Yilong; Liu, Xubo; Gandha, Kinjal; Vuong, Nguyen V.; Yang, Y. B.; Yang, Jinbo; Poudyal, Narayan; Cui, Jun; Liu, J.Ping

    2014-05-07T23:59:59.000Z

    Bulk anisotropic composite magnets based on MnBi/Co(Fe) exhibiting the different morphology of the soft magnetic phase were prepared by powder metallurgy processing. First, single-phase MnBi bulk magnets were produced using a maximum energy product [(BH)m] of 6.3 MGOe at room temperature. The nanoscale soft phase with the different morphology was then added to form a composite magnet. It was observed that addition of magnetic soft-phase nanoparticles and nanoflakes causes a dramatic coercivity reduction. However, the addition of soft magnetic phase nanowires enhanced the composite magnetization without sacrificing the coercivity. Nevertheless, a kink was still observed on the demagnetization curves and the coercivity decreased when the soft-phase content was larger than 10 wt. %, which was caused by the agglomeration of the soft phase nanowires that also led to a decreased degree of texture.

  19. High capacitive performance of nanostructured Mn-Ni-Co oxide composites for supercapacitor

    SciTech Connect (OSTI)

    Luo Jianmin [Institute of Applied Chemistry, Xinjiang University, Urumqi 830046 (China); Gao Bo [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhang Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)], E-mail: azhangxg@163.com

    2008-05-06T23:59:59.000Z

    Nanostructured Mn-Ni-Co oxide composites (MNCO) were prepared by thermal decomposition of the precursor obtained by chemical co-precipitation of Mn, Ni and Co salts. The chemical composition and morphology were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The electrochemical capacitance of MNCO electrode was examined by cyclic voltammetry, impedance and galvanostatic charge-discharge measurements. The results showed that MNCO electrode exhibited the good electrochemical characteristics. A maximum capacitance value of 1260 F g{sup -1} could be obtained within the potential range of -0.1 to 0.4 V versus saturated calomel electrode (SCE) in 6 mol L{sup -1} KOH electrolyte.

  20. Homogeneity testing and quantitative analysis of manganese (Mn) in vitrified Mn-doped glasses by laser-induced breakdown spectroscopy (LIBS)

    SciTech Connect (OSTI)

    Unnikrishnan, V. K.; Nayak, Rajesh; Kartha, V. B.; Santhosh, C., E-mail: santhosh.cls@manipal.edu, E-mail: unnikrishnan.vk@manipal.edu [Department of Atomic and Molecular Physics, Manipal University, Manipal (India); Sonavane, M. S. [Nuclear Recycle Board, Bhabha Atomic Research Centre, Mumbai (India); Yeotikar, R. G. [Process Development Division, Bhabha Atomic Research Centre, Mumbai (India); Shah, M. L.; Gupta, G. P.; Suri, B. M. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-09-15T23:59:59.000Z

    Laser-induced breakdown spectroscopy (LIBS), an atomic emission spectroscopy method, has rapidly grown as one of the best elemental analysis techniques over the past two decades. Homogeneity testing and quantitative analysis of manganese (Mn) in manganese-doped glasses have been carried out using an optimized LIBS system employing a nanosecond ultraviolet Nd:YAG laser as the source of excitation. The glass samples have been prepared using conventional vitrification methods. The laser pulse irradiance on the surface of the glass samples placed in air at atmospheric pressure was about 1.7×10{sup 9} W/cm{sup 2}. The spatially integrated plasma emission was collected and imaged on to the spectrograph slit using an optical-fiber-based collection system. Homogeneity was checked by recording LIBS spectra from different sites on the sample surface and analyzing the elemental emission intensities for concentration determination. Validation of the observed LIBS results was done by comparison with scanning electron microscope- energy dispersive X-ray spectroscopy (SEM-EDX) surface elemental mapping. The analytical performance of the LIBS system has been evaluated through the correlation of the LIBS determined concentrations of Mn with its certified values. The results are found to be in very good agreement with the certified concentrations.

  1. Thermoelectric study of crossroads material MnTe via sulfur doping

    SciTech Connect (OSTI)

    Xie, Wenjie, E-mail: xie@imw.uni-stuttgart.de; Populoh, Sascha; Sagarna, Leyre; Trottmann, Matthias [Empa–Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Uberlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ga??zka, Krzysztof [Empa–Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Uberlandstrasse 129, CH-8600 Dübendorf (Switzerland); Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern (Switzerland); Xiao, Xingxing [Institute for Materials Science, University of Stuttgart, DE-70569 Stuttgart (Germany); Liu, Yufei; He, Jian [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634-0978 (United States); Weidenkaff, Anke [Empa–Swiss Federal Laboratories for Materials Science and Technology, Solid State Chemistry and Catalysis, Uberlandstrasse 129, CH-8600 Dübendorf (Switzerland); Institute for Materials Science, University of Stuttgart, DE-70569 Stuttgart (Germany)

    2014-03-14T23:59:59.000Z

    Here, we report thermoelectric study of crossroads material MnTe via iso-electronic doping S on the Te-site. MnTe{sub 1-x}S{sub x} samples with nominal S content of x?=?0.00, 0.05, and 0.10 were prepared using a melt-quench method followed by pulverization and spark plasma sintering. The X-ray powder diffraction, scanning electron microscopy, and ZAF-corrected compositional analysis confirmed that S uniformly substitutes Te up to slightly over 2%. A higher content of S in the starting materials led to the formation of secondary phases. The thermoelectric properties of MnTe{sub 1-x}S{sub x} samples were characterized by means of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 300?K to 773?K. Furthermore, Hall coefficient measurements and a single parabolic band model were used to help gain insights on the effects of S-doping on the scattering mechanism and the carrier effective mass. As expected, S doping not only introduced hole charge carriers but also created short-range defects that effectively scatter heat-carrying phonons at elevated temperatures. On the other hand, we found that S doping degraded the effective mass. As a result, the ZT of MnTe{sub 0.9}S{sub 0.1} was substantially enhanced over the pristine sample near 400?K, while the improvement of ZT became marginal at elevated temperatures. A ZT???0.65 at 773?K was obtained in all three samples.

  2. Magnetostructure of MnAs on GaAs revisited E. Bauer,1,2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    introduced a model in which the crystal changed from a high spin state in the phase to a low spin state change during the phase transition is connected with a change of the sign of the exchange constant via material. hal-00193844,version1-4Dec2007 #12;3 FIG. 1. Structure of MnAs. (a) Hexagonal phase (NiAs type

  3. Solar DEM Models : A solar image in color band b, mn pixels,

    E-Print Network [OSTI]

    Wolfe, Patrick J.

    Solar DEM Models : A solar image in color band b, m×n pixels, containing a particular solar feature, for t = 1, 2, . . . , T. btM sianFieldRandomGaus I M I I bbb T t bbtt bbb bb 2 1 2 )( #12;Solar DEM.bI : the measure error of the ith row and jth column pixel of the certain image in color band b. ijbe #12;Solar DEM

  4. Magnetism in La?O?(Fe??xMnx)?Se? tuned by Fe/Mn ratio

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lei, Hechang; Bozin, Emil S.; Llobet, A.; Ivanovski, V.; Koteski, V.; Belosevic-Cavor, J.; Cekic, B.; Petrovic, C.

    2012-09-01T23:59:59.000Z

    We report the evolution of structural and magnetic properties in La?O?(Fe??xMnx)?Se?. Heat capacity and bulk magnetization indicate an increased ferromagnetic component of the long-range magnetic order and possible increased degree of frustration. Atomic disorder on Fe(Mn) sites suppresses the temperature of the long-range order whereas intermediate alloys show a rich magnetic phase diagram.

  5. Epitaxial {tau} phase MnAl thin films on MgO (001) with thickness-dependent magnetic anisotropy

    SciTech Connect (OSTI)

    Cui Yishen; Chen Wei [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Yin Wenjing; Lu Jiwei [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2011-11-15T23:59:59.000Z

    In this study, ferromagnetic MnAl films were prepared by alternating Al/Mn quasi-monolayer deposition using a novel biased target ion beam deposition (BTIBD) technique. XRD results showed that the magnetic {tau} phase was well formed in MnAl thin films ({approx}10 nm), which grew epitaxially on single crystal MgO (001) substrates. The optimized saturation magnetization was {approx}394 emu/cc. Furthermore, we observed a thickness-dependent uniaxial anisotropy in ferromagnetic MnAl films, which was attributed to the change of the tetragonal lattice distortion as a function of film thickness. The relationship between the film thicknesses and saturation magnetizations suggested the existence of a magnetically dead layer {approx}2.7 nm with an extrapolated saturation moment around 523 emu/cc ({approx}1.90 {mu}{sub B}/Mn). This value has exceeded the experimental value in bulk materials and is close to the theoretically predicted magnetization ({approx}1.975 {mu}{sub B}/Mn).

  6. First-principles calculations of the electronic, vibrational, and elastic properties of the magnetic laminate Mn?GaC

    SciTech Connect (OSTI)

    Thore, A., E-mail: andth@ifm.liu.se; Dahlqvist, M., E-mail: madah@ifm.liu.se, E-mail: bjoal@ifm.liu.se, E-mail: johro@ifm.liu.se; Alling, B., E-mail: madah@ifm.liu.se, E-mail: bjoal@ifm.liu.se, E-mail: johro@ifm.liu.se; Rosén, J., E-mail: madah@ifm.liu.se, E-mail: bjoal@ifm.liu.se, E-mail: johro@ifm.liu.se [Thin Film Physics Division, Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2014-09-14T23:59:59.000Z

    In this paper, we report the by first-principles predicted properties of the recently discovered magnetic MAX phase Mn?GaC. The electronic band structure and vibrational dispersion relation, as well as the electronic and vibrational density of states, have been calculated. The band structure close to the Fermi level indicates anisotropy with respect to electrical conductivity, while the distribution of the electronic and vibrational states for both Mn and Ga depend on the chosen relative orientation of the Mn spins across the Ga sheets in the Mn–Ga–Mn trilayers. In addition, the elastic properties have been calculated, and from the five elastic constants, the Voigt bulk modulus is determined to be 157?GPa, the Voigt shear modulus 93?GPa, and the Young's modulus 233?GPa. Furthermore, Mn?GaC is found relatively elastically isotropic, with a compression anisotropy factor of 0.97, and shear anisotropy factors of 0.9 and 1, respectively. The Poisson's ratio is 0.25. Evaluated elastic properties are compared to theoretical and experimental results for M?AC phases where M?=?Ti, V, Cr, Zr, Nb, Ta, and A?=?Al, S, Ge, In, Sn.

  7. Mn$_3$O$_4$(001) film growth on Ag(001) - a systematic study using NEXAFS, STM, and LEED

    E-Print Network [OSTI]

    Gillmeister, Konrad; Shantyr, Roman; Trautmann, Martin; Meinel, Klaus; Chassé, Angelika; Schindler, Karl-Michael; Neddermeyer, Henning; Widdra, Wolf

    2015-01-01T23:59:59.000Z

    The film growth of Mn$_3$O$_4$(001) films on Ag(001) up to film thicknesses of almost seven unit cells of Mn$_3$O$_4$ has been monitored using a complementary combination of near-edge X-ray absorption fine structure spectroscopy (NEXAFS), scanning tunneling microscopy (STM), and low-energy electron diffraction (LEED). The oxide films have been prepared by molecular beam epitaxy. Using NEXAFS, the identity of the Mn oxide has clearly been determined as Mn$_3$O$_4$. For the initial stages of growth, oxide islands with p(2$\\times$1) and p(2$\\times$2) structures are formed, which are embedded into the substrate. For Mn$_3$O$_4$ coverages up to 1.5 unit cells a p(2$\\times$1) structure of the films is visible in STM and LEED. Further increase of the thickness leads to a phase transition of the oxide films resulting in an additional c(2$\\times$2) structure with a 45$^\\circ$ rotated atomic pattern. The emerging film structures are discussed on the basis of a sublayer model of the Mn$_3$O$_4$ spinel unit cell. While t...

  8. Strain-induced modification in the magnetic properties of Mn{sub 5}Ge{sub 3} thin films

    SciTech Connect (OSTI)

    Dung, Dang Duc [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of) [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Department of General Physics, School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Odkhuu, Dorj; Cheol Hong, Soon; Cho, Sunglae [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of)] [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Thanh Vinh, Le [Aix Marseille Université, CNRS, CINaM-UMR 7325, 13288 Marseille (France)] [Aix Marseille Université, CNRS, CINaM-UMR 7325, 13288 Marseille (France)

    2013-08-21T23:59:59.000Z

    Epitaxial ferromagnetic Mn{sub 5}Ge{sub 3} thin films were stabilized on GaSb(001) and GaAs(001) substrates using molecular beam epitaxy. Compared to bulk Mn{sub 5}Ge{sub 3} materials, an enhancement of the Curie temperature above 350 K and about 320 K was observed for Mn{sub 5}Ge{sub 3}/GaAs(001) and Mn{sub 5}Ge{sub 3}/GaSb(001) heterostructures, respectively. The magnetization was found to decrease from 323 to 245 emu/cm{sup 3} for films grown on GaSb(001) and GaAs(001). Anomalous Hall effect measurements provide evidence of the strain-induced large spin polarization from density-functional study. Furthermore, our calculated results in bulk Mn{sub 5}Ge{sub 3} under strain indicate that the strain is the origin of different physical properties of Mn{sub 5}Ge{sub 3} grown on different substrates.

  9. Preparation and characterization of nanostructured NiO/MnO{sub 2} composite electrode for electrochemical supercapacitors

    SciTech Connect (OSTI)

    Liu Enhui [College of Chemistry, Xiangtan University, Hunan 411105 (China)], E-mail: liuenhui99@sina.com.cn; Li Wen; Li Jian; Meng Xiangyun; Ding Rui; Tan Songting [College of Chemistry, Xiangtan University, Hunan 411105 (China)

    2009-05-06T23:59:59.000Z

    Nanostructured nickel-manganese oxides composite was prepared by the sol-gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO{sub 2} samples exhibit higher surface area of 130-190 m{sup 2} g{sup -1}. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO{sub 2}. When the mass ratio of MnO{sub 2} and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO{sub 2} calculated from the cyclic voltammetry curves is 453 F g{sup -1}, for pure NiO and MnO{sub 2} are 209, 330 F g{sup -1} in 6 mol L{sup -1} KOH electrolyte and at scan rate of 10 mV s{sup -1}, respectively. The specific capacitance of NiO/MnO{sub 2} electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties.

  10. Magnetic anisotropy barrier for spin tunneling in Mn{sub 12}O{sub 12} molecules

    SciTech Connect (OSTI)

    Pederson, M.R. [Center for Computational Materials Science--6392, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Center for Computational Materials Science--6392, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States); Khanna, S.N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    1999-10-01T23:59:59.000Z

    Electronic structure calculations on the nature of electronic states and the magnetic coupling in Mn-acetate [Mn{sub 12}O{sub 12}(RCOO){sub 16}(H{sub 2}O){sub 4}] molecules have been been carried out within the generalized gradient approximation to the density functional formalism. Our studies on this 100-atom molecule illustrate the role of the nonmagnetic carboxyl host in stabilizing the ferrimagnetic Mn{sub 12}O{sub 12} core and provide estimates of the local magnetic moment at the various sites. We provide a first density-functional-based prediction of the second-order magnetic anisotropy energy of this system. Results are in excellent agreement with experiment. To perform these calculations we introduce a simplified exact method for spin-orbit coupling and magnetic anisotropy energies in multicenter systems. This method is free of shape approximations and has other advantages as well. First, it is valid for periodic boundary conditions or finite systems and is independent of basis set choice. Second, the method does not require the calculation of electric field. Third, for applications to systems with a finite energy gap between occupied and unoccupied electronic states, a perturbative expansion allows for a simple determination of the magnetic anisotropy energy. {copyright} {ital 1999} {ital The American Physical Society}

  11. Carriers-mediated ferromagnetic enhancement in Al-doped ZnMnO dilute magnetic semiconductors

    SciTech Connect (OSTI)

    Saleem, Murtaza [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Siddiqi, Saadat A. [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS Institute of Information Technology, Defence Road, Off Raiwind Road, Lahore (Pakistan); Atiq, Shahid, E-mail: shahidatiqpasrur@yahoo.com [Centre of Excellence in Solid State Physics, University of the Punjab, Lahore-54590 (Pakistan); Anwar, M. Sabieh; Hussain, Irshad [School of Science and Engineering (SSE), Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A. Lahore Cantt-54792 (Pakistan); Alam, Shahzad [Pakistan Council for Scientific and Industrial Research (PCSIR) Laboratories Complex, Lahore (Pakistan)

    2011-11-15T23:59:59.000Z

    Nano-crystalline Zn{sub 0.95-x}Mn{sub 0.05}Al{sub x}O (x = 0, 0.05, 0.10) dilute magnetic semiconductors (DMS) were synthesized by sol-gel derived auto-combustion. X-ray diffraction (XRD) analysis shows that the samples have pure wurtzite structure typical of ZnO without the formation of secondary phases or impurity. Crystallite sizes were approximated by Scherrer formula while surface morphology and grain sizes were measured by field emission scanning electron microscopy. Incorporation of Mn and Al into the ZnO structure was confirmed by energy-dispersive X-ray analysis. Temperature dependent electrical resistivity measurements showed a decreasing trend with the doping of Al in ZnMnO, which is attributable to the enhancement of free carriers. Vibrating sample magnetometer studies confirmed the presence of ferromagnetic behavior at room temperature. The results indicate that Al doping results in significant variation in the concentration of free carriers and correspondingly the carrier-mediated magnetization and room temperature ferromagnetic behavior, showing promise for practical applications. We attribute the enhanced saturation magnetization and electrical conductivity to the exchange interaction mediated by free electrons.

  12. Sign change of exchange bias in [Pt/Co]{sub 3}/IrMn multilayer

    SciTech Connect (OSTI)

    Yoon, Seungha; Kwon, Joonhyun; Cho, B. K., E-mail: chobk@gist.ac.kr [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2014-05-07T23:59:59.000Z

    The properties of exchange bias in a multilayer of [Pt(1.0?nm)/Co(1.0?nm)]{sub 2}/Pt(t{sub Pt} nm)/Co(1.0?nm)/ IrMn(12.0?nm) were investigated with a variation of Pt layer thickness, t{sub Pt}. For t{sub Pt}???1.6?nm, it was typically observed that Co layers were ferromagnetically coupled while IrMn layer exhibited negative exchange bias. With increasing Pt thickness, antiferromagnetic (AF) interlayer coupling strength increased and caused AF spin configuration between the Co layers. With further increasing of Pt thickness (t{sub Pt}?=?2.5?nm), the exchange bias between Co and IrMn layers was changed from negative to positive. Therefore, a large enhancement of AF interlayer coupling induced the sign change of exchange bias from negative to positive and resulted in a drastic change of switching behavior in a magnetization reversal. Both extraordinary Hall-effect and magnetoresistance were measured to verify the exchange bias direction and spin configurations upon magnetization reversal.

  13. Structural and Magnetic Properties of MCl2 (M = Fe, Mn, Co): Acetonitrile Solvates

    SciTech Connect (OSTI)

    Pokhodnya,K.; Bonner, M.; DiPasquale, A.; Rheingold, A.; Her, J.; Stephens, P.; Park, J.; Kennon, B.; Arif, A.; Miller, J.

    2007-01-01T23:59:59.000Z

    M{sup II}Cl{sub 2} (M = Mn, Fe, Co) as their acetonitrile solvates were isolated, and their structural, spectroscopic, and magnetic properties were studied. MCl{sub 2}(NCMe){sub 2} (M = Fe, Mn) form 1-D chains of octahedral M{sup II} ions with four bridging chlorides and two axial MeCN's. The presence of an axial distortion for MFe causes a significant magnetic anisotropy that increases significantly below 150 K; however, {chi}{sub av} [=({chi}{sub {parallel}} + 2{chi}{sub {perpendicular}})/3] almost coincides with the value obtained on a polycrystalline sample. MnCl{sub 2}(NCMe){sub 2} is a paramagnet with a weak antiferromagnetic coupling. Annealing FeCl{sub 2}(NCMe){sub 2} at 55 {sup o}C forms the monosolvate of FeCl{sub 2}(NCMe) composition in which two chains collapse into a double chain with formation of Fe-Cl bonding such that half of the {mu}-Cl's becomes {mu}{sub 3}-Cl's. This material orders magnetically below {Tc} = 4.3 K. For M = Co, paramagnetic tetrahedral [CoCl{sub 3}(NCMe)]{sup -} anions are isolated.

  14. Redox Active Layer-by-Layer Structures containing MnO2 Nanoparticles

    SciTech Connect (OSTI)

    Bazito, Fernanda; O'Brien, Robert; Buttry, Daniel A.

    2005-02-01T23:59:59.000Z

    Nanoscale materials provide unique properties that will enable new technologies and enhance older ones. One area of intense activity in which nanoscale materials are being used is in the development of new functional materials for battery applications. This effort promises superior materials with properties that circumvent many of the problems associated with traditional battery materials. Previously we have worked on several approaches for using nanoscale materials for application as cathode materials in rechargeable Li batteries. Our recent work has focused on synthesizing MnO2 nanoparticles and using these in layer-by-layer (LbL) structures to probe the redox properties of the nanoparticles. We show that the aqueous colloidal nanoparticles produced by butanol reduction of tetramethylammonium permanganate can be trapped in thin films using a layer-by-layer deposition approach, and that these films are both redox active and exhibit kinetically facile electrochemical responses. We show cyclic voltammetry of MnO2 colloidal nanoparticles entrapped in a LbL thin film at an ITO electrode surface using poly(diallyldimethylammonium chloride) (PDDA). CV experiments demonstrate that Li+ insertion accompanies Mn(IV) reduction in LiClO4 supporting electrolytes, and that reduction is hindered in supporting electrolytes containing only tetrabutylammonium cations. We also show that electron propagation through multilayer films is facile, suggesting that electrons percolate through the films via electron exchange between nanoparticles.

  15. Why MnIn{sub 2}O{sub 4} spinel is not a transparent conducting oxide?

    SciTech Connect (OSTI)

    Martinez-Lope, M.J. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049 Madrid (Spain); Retuerto, M. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049 Madrid (Spain); Department of Chemistry, Rutgers State University of New Jersey, Piscataway, NJ 08854-8087 (United States); Calle, C. de la [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049 Madrid (Spain); Porcher, Florence [Laboratoire Leon Brillouin, CEA/Saclay, 91191 Gif Sur Ivette Cedex, France. (France); Alonso, J.A., E-mail: ja.alonso@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049 Madrid (Spain)

    2012-03-15T23:59:59.000Z

    The title compound has been synthesized by a citrate technique. The crystal structure has been investigated at room temperature from high-resolution neutron powder diffraction (NPD) data. It crystallizes in a cubic spinel structure, space group Fd3-bar m, Z=8, with a=9.0008(1) A at 295 K. It exhibits a crystallographic formula (Mn{sub 0.924(2)}In{sub 0.076(2)}){sub 8a}(In{sub 1.804(2)}Mn{sub 0.196(2)}){sub 16d}O{sub 4}, where 8a and 16d stand for the tetrahedral and octahedral sites of the spinel structure, respectively, with a slight degree of inversion, {lambda}=0.08. MnIn{sub 2}O{sub 4} shows antiferromagnetic interactions below T{sub N} Almost-Equal-To 40 K, due to the statistical distribution of Mn ions over the two available sites. Unlike the related MgIn{sub 2}O{sub 4} and CdIn{sub 2}O{sub 4} spinels, well known as transparent conducting oxides, MnIn{sub 2}O{sub 4} is not transparent and shows a poor conductivity ({sigma}=0.38 S cm{sup -1} at 1123 K): the presence of Mn ions, able to adopt mixed valence states, localizes the charges that, otherwise, would be delocalized in the spinel conduction band. - Graphical Abstract: From NPD data the crystallographic formula (Mn{sub 0.924(2)}In{sub 0.076(2)}){sub 8a}(In{sub 1.804(2)}Mn{sub 0.196(2)}){sub 16d}O{sub 4}, shows a slight degree of inversion, {lambda}=0.08 and a certain In deficiency. The presence of Mn ions, able to adopt mixed oxidation states, localize the charges that, otherwise, would be delocalized in the spinel conduction band; the presence of localized Mn{sup 2+} and Mn{sup 3+} ions provides the characteristic brown color. Highlights: Black-Right-Pointing-Pointer Accurate structural determination from NPD data: inversion degree (8%), and In deficiency. Black-Right-Pointing-Pointer Bond-valence indicates Mn{sup 2+}-Mn{sup 3+} ions; edge-sharing octahedra contain 90% In{sup 3+}+10% Mn{sup 3+} cations. Black-Right-Pointing-Pointer Conductivity several orders of magnitude lower than those of MgIn{sub 2}O{sub 4} or CdIn{sub 2}O{sub 4}. Black-Right-Pointing-Pointer Variability of Mn oxidation states cancels any electron-doping effect, emptying conduction band of mobile charge carriers. Black-Right-Pointing-Pointer Curie-Weiss behavior confirming the determined charge distribution.

  16. Electronic states and cyclotron resonance in n-type InMnAs G. D. Sanders, Y. Sun, F. V. Kyrychenko, and C. J. Stanton

    E-Print Network [OSTI]

    Kono, Junichiro

    and their heterostructures with AlGaSb, the first grown III-V magnetic semiconductor,1,5,6 serve as a prototype s : 75.50.Pp, 78.20.Ls, 78.40.Fy I. INTRODUCTION Recently, there has been much interest in III-V magnetic semiconductors such as InMnAs Ref. 1 and GaMnAs Ref. 2 . The ferromagnetic exchange coupling between Mn ions

  17. Magnetic ordering in the spinel compound LiMn2-xLixO4,,x=0,0.04... John Gaddy,1

    E-Print Network [OSTI]

    Montfrooij, Wouter

    .1063/1.3073660 The ground state properties of the known lithium-based cubic spinel compounds LiT2O4 range from BCS-range antiferromagnetic order. In contrast, whereas lithium-substituted Li Mn2-xLix O4 also undergoes a charge eightfold rings.6 The Mn4+ rings only interact with other rings via the intervening Mn3+ ions. When cooled

  18. Magnetic properties of ion implanted Ge{sub 1-x}Mn{sub x} thin films solidified through pulsed laser melting

    SciTech Connect (OSTI)

    Commisso Dolph, Melissa [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Kim, Taeseok; Recht, Daniel; Aziz, Michael J. [Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Yin Wenjing; Fan Wenbin; Yu Jiani; Lu Jiwei [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2011-05-01T23:59:59.000Z

    Ge{sub 1-x}Mn{sub x} thin films with an average Mn concentration of 0.64 at. % were fabricated through Mn ion implantation into crystalline germanium-on-insulator wafers. Implantation damage was removed and crystallinity restored by pulsed laser melting from a single 30-ns 308-nm XeCl{sup +} excimer laser pulse. Resolidified films demonstrated higher Curie temperatures but smaller saturation magnetizations than those of both as-implanted films and implanted films subjected to rapid thermal annealing. These findings are attributed to the redistribution of Mn during solidification.

  19. Effect of disorder on the magnetic properties of cubic Mn{sub 2}Ru{sub x}Ga compounds: A first-principles study

    SciTech Connect (OSTI)

    Galanakis, I., E-mail: galanakis@upatras.gr [Department of Materials Science, School of Natural Sciences, University of Patras, GR-26504 Patra (Greece); Özdo?an, K., E-mail: kozdogan@yildiz.edu.tr [Department of Physics, Yildiz Technical University, 34210 ?stanbul (Turkey); ?a??o?lu, E., E-mail: e.sasioglu@fz-juelich.de; Blügel, S. [Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich (Germany)

    2014-07-21T23:59:59.000Z

    We perform first-principles electronic structure calculations to explain the anomalous magnetic behavior of the Mn{sub 2}Ru{sub x}Ga compounds upon Ru doping as shown experimentally recently by Kurt et al. [Phys. Rev. Lett. 112, 027201 (2014)]. Our results suggest that disorder caused by the distribution of the Mn and Ru atoms at various sites reproduces the experimental data. All compounds present antiparallel alignment of the neighboring Mn magnetic moments and, with the exception of Mn{sub 2}RuGa, none of them presents half metallic behavior.

  20. Combustion Synthesis of Nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1, 0.2) Carbon Composites

    E-Print Network [OSTI]

    Doeff, Marca M

    2010-01-01T23:59:59.000Z

    for Rechargeable Lithium Batteries. J. Electrochem. Soc.4 V Cathode Materials for Lithium Batteries. J. Electrochem.LiMnPO 4 for Lithium Ion Batteries. Electrochem. and Solid

  1. Transmission electron microscopy of RSP Fe/Cr/Mn/Mo/C alloy. [Fe-3 wt % Cr-2 wt % Mn-0. 5 wt % Mo, -0. 3 wt % C

    SciTech Connect (OSTI)

    Rayment, J.J.; Thomas, G.

    1982-03-01T23:59:59.000Z

    Rapid solidification processing (RSP) has been carried out on an Fe/Cr/Mn/Mo/C alloy using both electron-beam melting and piston-and-anvil techniques. Preliminary TEM results show RSP produces a refined duplex microstructure of ferrite and martensite, with a typical ferrite grain size of 0.50 - 3.0 microns. This RSP microstructure is significantly different from that observed in the conventionally austenitized and quenched alloys - a lath martensitic microstructure with thin films of retained interlath austenite. The morphological change produced by RSP is accompanied by an increase in hardness from 48R/sub c/ to 61R/sub c/ (approx. 480 to 720 VHN). It is intended to use electron-beam specimens to examine the potential beneficial effect of RSP upon sliding wear resistance and, by careful TEM studies, it will be possible to characterize the microstructure and its role in the hardness and wear behavior of the RSP alloy.

  2. Milagro's Sensitivity to GRBs Elizabeth Hays and David Noyes for the Milagro Calaboration

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    that the excess is a statistical fluctuation is less than 5s, then the GRB can be detected. Because the whole sky

  3. Zero-field signal in the electron paramagnetic resonance spectrum of Mn{sup +2} in silicate glasses

    SciTech Connect (OSTI)

    Rakhimov, Rakhim R. [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States)] [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Jones, David E. [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States)] [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States)

    2000-07-22T23:59:59.000Z

    A 9.4-9.8 GHz electron paramagnetic resonance (EPR) study of Mn{sup +2}-doped Na{sub 2}O-CaO-MgO-SiO{sub 2} glasses has revealed a nonresonant microwave magneto-absorption near zero magnetic field in addition to normal paramagnetic absorption due to Mn{sup +2} ions, electron spin S=5/2. The low-field response has an opposite phase relative to paramagnetic signal and is independent of the mutual orientation of the magnetic field of the microwave H{sub 1} and static magnetic field H. In contrast, the paramagnetic signal is different for perpendicular H{sub 1}(perpendicular sign)H and parallel H{sub 1}(parallel sign)H polarization of the microwave field, which is attributed to enhancement of forbidden magnetic dipolar transitions and suppression of the allowed transitions for parallel polarization. The low-field response is described in terms of microwave dielectric losses that derive from the magneto-induced charge migration in the first coordination sphere of Mn{sup +2}. As opposed to the spin-polarized tunneling that was described in ferromagnets between different valence forms of Mn, the observed effect is due to spin-dependent tunneling that occurs in the vicinity of Mn{sup +2} in a diluted paramagnetic system. (c) 2000 American Institute of Physics.

  4. Magnetovolume effect in Ho{sub 2}Fe{sub 17-x}Mn{sub x} compounds

    SciTech Connect (OSTI)

    Wang, J. L. [Institute for Superconductivity and Electronic Materials, University of Wollongong (Australia); Bragg Institute, ANSTO, Menai, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2600 (Australia); Studer, A. J.; Kennedy, S. J. [Bragg Institute, ANSTO, Menai, NSW 2234 (Australia); Zeng, R.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2600 (Australia)

    2012-04-01T23:59:59.000Z

    The structural and magnetic properties of seven compounds in the Ho{sub 2}Fe{sub 17-x}Mn{sub x} series (x = 0-5) have been investigated. The spontaneous magnetization M{sub s} at 10 K exhibits a minimum at x{approx_equal} 3.8 while the 3d-sublattice magnetization M{sub T} is found to decrease at {approx} -3.4 {mu}{sub B}/per Mn atom compared with the rate of {approx}-2.0 {mu}{sub B}/per Mn atom expected from a simple dilution model. All of the Ho{sub 2}Fe{sub 17-x}Mn{sub x} compounds exhibit anisotropic thermal expansion below their Curie temperatures leading to the presence of strong magnetovolume effects and Invar-type behavior below T{sub C}. An approximately zero volume thermal expansion has been detected between 10 K and 270 K for Ho{sub 2}Fe{sub 17}. The maximum magnetic entropy changes for Ho{sub 2}Fe{sub 17-x}Mn{sub x} with x = 0 and 2.0 are 3.2 J kg{sup -1} K{sup -1} around T{sub C} {approx} 336 K and 2.7 J kg{sup -1} K{sup -1} around T{sub C} {approx} 302 K, respectively, for magnetic field change of B = 0-5 T.

  5. Structural properties and large coercivity of bulk Mn{sub 3?x}Ga (0 ? x ? 1.15)

    SciTech Connect (OSTI)

    Wei, J. Z.; Wu, R.; Yang, Y. B.; Chen, X. G.; Xia, Y. H.; Yang, Y. C.; Wang, C. S. [School of Physics, Peking University, Beijing 100871 (China); Yang, J. B., E-mail: jbyang@pku.edu.cn [School of Physics, Peking University, Beijing 100871 (China); State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)

    2014-05-07T23:59:59.000Z

    The tetragonal DO{sub 22} phase of the Mn{sub 3?x}Ga compounds, with x varying from 0 to 1.15, has been successfully synthesized by annealing the ingots with the cubic ?-phase. It is found that the lattice parameter a of the tetragonal cell remains almost constant, while the lattice parameter c increases significantly as x varies from 0 to 1.15. In the meantime, the magnetization of Mn{sub 3?x}Ga (at 7?T) increases dramatically with increasing x. A substitution model, which is different to the model with manganese vacancies, is proposed to explain these changes. According to this model, the increase of the lattice parameter c and the magnetization with x can be explained by an assumption that Mn atoms at 2b sites are preferentially substituted by larger and nonmagnetic Ga atoms. A coercivity which is higher than that of other bulk Mn{sub 3?x}Ga alloys ever reported is achieved. Coercivities as large as iHc?=?21.4 kOe and 18.2 kOe are obtained for Mn{sub 3.0}Ga at 5?K and 300?K, respectively.

  6. Delocalization and hybridization enhance the magnetocaloric effect in Ni2Mn0.75Cu0.25Ga

    SciTech Connect (OSTI)

    Roy, Sujoy; Blackburn, E.; Valvidares, S. M.; Fitzsimmons, M. R.; Vogel, Sven C.; Khan, M.; Dubenko, I.; Stadler, S.; Ali, N.; Sinha, S. K.; Kortright, J. B.

    2008-11-26T23:59:59.000Z

    In view of the looming energy crisis facing our planet, attention increasingly focuses on materials potentially useful as a basis for energy saving technologies. The discovery of giant magnetocaloric (GMC) compounds - materials that exhibit especially large changes in temperature as the externally applied magnetic field is varied - is one such compound 1. These materials have potential for use in solid state cooling technology as a viable alternative to existing gas based refrigeration technologies that use choro-fluoro - and hydro-fluoro-carbon chemicals known to have a severe detrimental effect on human health and environment 2,3. Examples of GMC compounds include Gd5(SiGe)4 4, MnFeP1-xAsx 5 and Ni-Mn-Ga shape memory alloy based compounds 6-8. Here we explain how the properties of one of these compounds (Ni2MnGa) can be tuned as a function of temperature by adding dopants. By altering the free energy such that the structural and magnetic transitions coincide, a GMC compound that operates at just the right temperature for human requirements can be obtained 9. We show how Cu, substituted for Mn, pulls the magnetic transition downwards in temperature and also, counterintuitively, increases the delocalization of the Mn magnetism. At the same time, this reinforces the Ni-Ga chemical bond, raising the temperature of the martensite-austenite transition. At 25percent doping, the two transitions coincide at 317 K.

  7. Electron spin resonance investigation of Mn^{2+} ions and their dynamics in manganese doped SrTiO_3

    E-Print Network [OSTI]

    V. V. Laguta; I. V. Kondakova; I. P. Bykov; M. D. Glinchuk; P. M. Vilarinho; A. Tkach; L. Jastrabik

    2007-02-28T23:59:59.000Z

    Using electron spin resonance, lattice position and dynamic properties of Mn2+ ions were studied in 0.5 and 2 % manganese doped SrTiO3 ceramics prepared by conventional mixed oxide method. The measurements showed that Mn2+ ions substitute preferably up to 97 % for Sr if the ceramics is prepared with a deficit of Sr ions. Motional narrowing of the Mn2+ ESR spectrum was observed when temperature increases from 120 K to 240-250 K that was explained as a manifestation of off-center position of this ion at the Sr site. From the analysis of the ESR spectra the activation energy Ea = 86 mV and frequency factor 1/?0 ? (2-10)x10^(-14) 1/s for jumping of the impurity between symmetrical off-center positions were determined. Both values are in agreement with those derived previously from dielectric relaxation. This proves the origin of dielectric anomalies in SrTiO3:Mn as those produced by the reorientation dynamics of Mn2+ dipoles.

  8. Phase transformation during mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si alloys

    SciTech Connect (OSTI)

    Amini, Rasool, E-mail: ramini2002@gmail.com [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Shamsipoor, Ali [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Ghaffari, Mohammad [Department of Electrical and Electronics Engineering, UNAM-National Institute of Materials Science and Nanotechnology Bilkent University, Ankara 06800 (Turkey); Alizadeh, Morteza [Department of Materials Science and Engineering, Shiraz University of Technology, 71555-313 Shiraz (Iran, Islamic Republic of); Okyay, Ali Kemal [Department of Electrical and Electronics Engineering, UNAM-National Institute of Materials Science and Nanotechnology Bilkent University, Ankara 06800 (Turkey)

    2013-10-15T23:59:59.000Z

    Mechano-synthesis of Fe–32Mn–6Si alloy by mechanical alloying of the elemental powder mixtures was evaluated by running the ball milling process under an inert argon gas atmosphere. In order to characterize the as-milled powders, powder sampling was performed at predetermined intervals from 0.5 to 192 h. X-ray florescence analyzer, X-ray diffraction, scanning electron microscope, and high resolution transmission electron microscope were utilized to investigate the chemical composition, structural evolution, morphological changes, and microstructure of the as-milled powders, respectively. According to the results, the nanocrystalline Fe–Mn–Si alloys were completely synthesized after 48 h of milling. Moreover, the formation of a considerable amount of amorphous phase during the milling process was indicated by quantitative X-ray diffraction analysis as well as high resolution transmission electron microscopy image and its selected area diffraction pattern. It was found that the ?-to-? and subsequently the amorphous-to-crystalline (especially martensite) phase transformation occurred by milling development. - Graphical abstract: Mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si shape memory alloys in the powder form: amorphous phase formation, ?-to-? phase transformation, mechano-crystallization of the amorphous, and martensite phase formation during the process. Highlights: • During MA, the ?-to-? phase transformation and amorphization occurred. • Mechano-crystallization of the amorphous phase occurred at sufficient milling time. • The formation of high amount of ?-martensite was evidenced at high milling times. • The platelet, spherical, and then irregular particle shapes was extended by MA. • By MA, the particles size was increased, then reduced, and afterward re-increased.

  9. Surface structures of Al-Pd-Mn and Al-Cu-Fe icosahedral quasicrystals

    SciTech Connect (OSTI)

    Shen, Z.

    1999-02-12T23:59:59.000Z

    In this dissertation, the author reports on the surface structure of i-Al-Pd-Mn twofold, threefold, fivefold and i-Al-Cu-Fe fivefold surfaces. The LEED studies indicate the existence of two distinct stages in the regrowth of all four surfaces after Ar{sup +} sputtering. In the first stage, upon annealing at relatively low temperature: 500K--800K (depending on different surfaces), a cubic phase appears. The cubic LEED patterns transform irreversibly to unreconstructed quasicrystalline patterns upon annealing to higher temperatures, indicating that the cubic overlayers are metastable. Based upon the data for three chemically-identical, but symmetrically-inequivalent surfaces, a model is developed for the relation between the cubic overlayers and the quasicrystalline substrate. The model is based upon the related symmetries of cubic close-packed and icosahedral-packed materials. These results may be general among Al-rich, icosahedral materials. STM study of Al-Pd-Mn fivefold surface shows that terrace-step-kink structures start to form on the surface after annealing above 700K. Large, atomic ally-flat terraces were formed after annealing at 900K. Fine structures with fivefold icosahedral symmetry were found on those terraces. Data analysis and comparison of the STM images and structure model of icosahedral Al-Pd-Mn suggest that the fine structures in the STM images may be the pseudo Mackay (PMI) clusters which are the structure units of the structure model. Based upon his results, he can conclude that quasicrystalline structures are the stable structures of quasicrystal surfaces. In other words, quasicrystalline structures extend from the bulk to the surface. As a result of the effort reported in this dissertation, he believes that he has increased his understanding of the surface structure of icosahedral quasicrystals to a new level.

  10. LiMn{sub 2}O{sub 4} nanoparticles anchored on graphene nanosheets as high-performance cathode material for lithium-ion batteries

    SciTech Connect (OSTI)

    Lin, Binghui; Yin, Qing; Hu, Hengrun; Lu, Fujia [School of Materials Science and Engineering, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China); Xia, Hui, E-mail: xiahui@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China); Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2014-01-15T23:59:59.000Z

    Nanocrystalline LiMn{sub 2}O{sub 4}/graphene nanosheets nanocomposite has been successfully synthesized by a one-step hydrothermal method without post-heat treatment. In the nanocomposite, LiMn{sub 2}O{sub 4} nanoparticles of 10–30 nm in size are well crystallized and homogeneously anchored on the graphene nanosheets. The graphene nanosheets not only provide a highly conductive matrix for LiMn{sub 2}O{sub 4} nanoparticles but also effectively reduce the agglomeration of LiMn{sub 2}O{sub 4} nanoparticles. The nanocrystalline LiMn{sub 2}O{sub 4}/graphene nanosheets nanocomposite exhibited greatly improved electrochemical performance in terms of specific capacity, cycle performance, and rate capability compared with the bare LiMn{sub 2}O{sub 4} nanoparticles. The superior electrochemical performance of the nanocrystalline LiMn{sub 2}O{sub 4}/graphene nanosheets nanocomposite makes it promising as cathode material for high-performance lithium-ion batteries. - Graphical abstract: Nanocrystalline LiMn{sub 2}O{sub 4}/graphene nanosheets (GNS) nanocomposite exhibit superior cathode performance for lithium-ion batteries compared to the bare LiMn{sub 2}O{sub 4} nanoparticles. Display Omitted - Highlights: • LiMn{sub 2}O{sub 4}/graphene nanocomposite is synthesized by a one-step hydrothermal method. • LiMn{sub 2}O{sub 4} nanoparticles are uniformly anchored on the graphene nanosheets. • The nanocomposite exhibits excellent cathode performance for lithium-ion batteries.

  11. Elastic Constants of Ni-Mn-Ga Magnetic Shape Memory Alloys

    SciTech Connect (OSTI)

    Stipcich, M. [Universitat de Barcelona; Manosa, L. [Universitat de Barcelona; Planes, A. [Universitat de Barcelona; Morin, M. [INSA de Lyon; Zarestky, Jerel L [ORNL; Lograsso, Tom [Ames Laboratory; Stassis, C. [Ames Laboratory

    2004-01-01T23:59:59.000Z

    We have measured the adiabatic second order elastic constants of two Ni-Mn-Ga magnetic shape memory crystals with different martensitic transition temperatures, using ultrasonic methods. The temperature dependence of the elastic constants has been followed across the ferromagnetic transition and down to the martensitic transition temperature. Within experimental errors no noticeable change in any of the elastic constants has been observed at the Curie point. The temperature dependence of the shear elastic constant C' has been found to be very different for the two alloys. Such a different behavior is in agreement with recent theoretical predictions for systems undergoing multi-stage structural transitions.

  12. Direct evidence of detwinning in polycrystalline Ni-Mn-Ga ferromagnetic shape memory alloys during deformation.

    SciTech Connect (OSTI)

    Nie, Z. H.; Lin Peng, R.; Johansson, S.; Oliver, E. C.; Ren, Y.; Wang, Y. D.; Liu, Y. D.; Deng, J. N.; Zuo, L.; Brown, D. E.; Northwestern Univ., China; Linkoping Univ.; Rutherford Appleton Lab.; Northern Illinois Univ.

    2008-01-01T23:59:59.000Z

    In situ time-of-flight neutron diffraction and high-energy x-ray diffraction techniques were used to reveal the preferred reselection of martensite variants through a detwinning process in polycrystalline Ni-Mn-Ga ferromagnetic shape memory alloys under uniaxial compressive stress. The variant reorientation via detwinning during loading can be explained by considering the influence of external stress on the grain/variant orientation-dependent distortion energy. These direct observations of detwinning provide a good understanding of the deformation mechanisms in shape memory alloys.

  13. Vacancy dynamic in Ni-Mn-Ga ferromagnetic shape memory alloys

    SciTech Connect (OSTI)

    Merida, D., E-mail: david.merida@ehu.es [Fisika Aplikatua II Saila, Euskal Herriko Unibertsitatea UPV/EHU, p.k. 644, 48080 Bilbao (Spain); Elektrizitate eta Elektronika Saila, Euskal Herriko Unibertsitatea UPV/EHU, p.k. 644, 48080 Bilbao (Spain); García, J. A. [Fisika Aplikatua II Saila, Euskal Herriko Unibertsitatea UPV/EHU, p.k. 644, 48080 Bilbao (Spain); BC Materials (Basque Centre for Materials, Application and Nanostructures), 48040 Leioa (Spain); Sánchez-Alarcos, V.; Pérez-Landazábal, J. I.; Recarte, V. [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadia, 31006 Pamplona (Spain); Plazaola, F. [Elektrizitate eta Elektronika Saila, Euskal Herriko Unibertsitatea UPV/EHU, p.k. 644, 48080 Bilbao (Spain)

    2014-06-09T23:59:59.000Z

    Vacancies control any atomic ordering process and consequently most of the order-dependent properties of the martensitic transformation in ferromagnetic shape memory alloys. Positron annihilation spectroscopy demonstrates to be a powerful technique to study vacancies in NiMnGa alloys quenched from different temperatures and subjected to post-quench isothermal annealing treatments. Considering an effective vacancy type the temperature dependence of the vacancy concentration has been evaluated. Samples quenched from 1173?K show a vacancy concentration of 1100?±?200?ppm. The vacancy migration and formation energies have been estimated to be 0.55?±?0.05?eV and 0.90?±?0.07?eV, respectively.

  14. Magnetoelastic Coupling and Symmetry Breaking in the Frustrated Antiferromagnet {alpha}-NaMnO{sub 2}

    SciTech Connect (OSTI)

    Giot, Maud [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion (Greece); ISIS, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Chilton-Didcot, OX11 0QX, Oxfordshire (United Kingdom); Chapon, Laurent C.; Radaelli, Paolo G. [ISIS, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Chilton-Didcot, OX11 0QX, Oxfordshire (United Kingdom); Androulakis, John; Lappas, Alexandros [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion (Greece); Green, Mark A. [NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland 20899-8562 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115 (United States)

    2007-12-14T23:59:59.000Z

    The magnetic and crystal structures of the {alpha}-NaMnO{sub 2} have been determined by high-resolution neutron powder diffraction. The system maps out a frustrated triangular spin lattice with anisotropic interactions that displays two-dimensional spin correlations below 200 K. Magnetic frustration is lifted through magneto-elastic coupling, evidenced by strong anisotropic broadening of the diffraction profiles at high temperature and ultimately by a structural phase transition at 45 K. In this low-temperature regime a three-dimensional antiferromagnetic state is observed with a propagation vector k=((1/2),(1/2),0)

  15. Oxidation Characteristics of Fe-18Cr-18Mn-stainless alloys

    SciTech Connect (OSTI)

    James Rawers

    2010-10-01T23:59:59.000Z

    Air oxidation studies of Fe-18Cr-18Mn stainless steels were conducted at 525°C, 625°C, and 725°C. Alloys were evaluated with respect to changes in oxidation properties as a result of interstitial additions of nitrogen and carbon and of minor solute additions of silicon, molybdenum, and nickel. Interstitial concentrations possibly had a small, positive effect on oxidation resistance. Minor solute additions significantly improved oxidation resistance but could also reduce interstitial solubility resulting in formation of chromium carbides. Loss of solute chromium resulted in a slight reduction in oxidation protection. Oxidation lasting over 500 hours produced a manganese rich, duplex oxide structure: an outer sesquioxide and an inner spinel oxide.

  16. Spin relaxation time dependence on optical pumping intensity in GaAs:Mn

    SciTech Connect (OSTI)

    Burobina, V. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah 84112-0830 (United States); Binek, Ch. [Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, Theodore Jorgensen Hall, 855 North 16th Street, University of Nebraska, P.O. Box 880299, Lincoln, Nebraska 68588-0299 (United States)

    2014-04-28T23:59:59.000Z

    We analyze the dependence of electron spin relaxation time on optical pumping intensity in a partially compensated acceptor semiconductor GaAs:Mn using analytic solutions for the kinetic equations of the charge carrier concentrations. Our results are applied to previous experimental data of spin-relaxation time vs. excitation power for magnetic concentrations of approximately 10{sup 17}?cm{sup ?3}. The agreement of our analytic solutions with the experimental data supports the mechanism of the earlier-reported atypically long electron-spin relaxation time in the magnetic semiconductor.

  17. Calculations of structural, elastic, electronic, magnetic and phonon properties of FeNiMnAl by the first principles

    SciTech Connect (OSTI)

    U?ur, ?ule [Central Research and Practice Laboratory (AH?LAB), Ahi Evran University, 40100 K?r?ehir (Turkey); ?yigör, Ahmet [Department of Physics, Faculty of Science, Gazi University, 06500 Ankara (Turkey)

    2014-10-06T23:59:59.000Z

    The electronic, elastic and dynamical properties of the quaternary alloy FeNiMnAl have been investigated using a pseudopotential plane wave method within the generalized gradient approximation (GGA). We determined the lattice parameters and the bulk modulus B. In addition, the elastic properties such as elastic constans (C{sub 11}, C{sub 12} and C{sub 44}), the shear modulus G, the young modulus E, the poisson's ratio ? and the B/G ratio are also given. The FeNiMnAl Heusler alloy exhibit a ferromagnetic half-metallic behavior with the total magnetic moment of 4.02 ?{sub B}. The phonon dispersion of FeNiMnAl has been performed using the density functional theory and the direct method with 2×2×2 supercell.

  18. Large positive magnetoresistance effects in the dilute magnetic semiconductor (Zn,Mn)Se in the regime of electron hopping

    SciTech Connect (OSTI)

    Jansson, F., E-mail: fjansson@abo.fi; Wiemer, M.; Gebhard, F.; Baranovskii, S. D. [Department of Physics and Material Sciences Center, Philipps-University, D-35032 Marburg (Germany); Nenashev, A. V. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Petznick, S.; Klar, P. J. [Institute of Experimental Physics I, Justus-Liebig-University Giessen, D-35392 Giessen (Germany); Hetterich, M. [Institut für Angewandte Physik and Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76131 Karlsruhe (Germany)

    2014-08-28T23:59:59.000Z

    Magnetoresistance in dilute magnetic semiconductors is studied in the hopping transport regime. Measurements performed on Cl-doped Zn{sub 1–x}Mn{sub x}Se with x?Mn atoms in their vicinity via the s-d exchange interaction. Compositional disorder, in particular, the random distribution of magnetic atoms, leads to a magnetic-field induced broadening of the donor energy distribution. As the energy distribution broadens, the electron transport is hindered and a large positive contribution to the magnetoresistance arises. This broadening of the donor energy distribution is largely sufficient to account for the experimentally observed magnetoresistance effects in n-type (Zn,Mn)Se with donor concentrations below the metal–insulator transition.

  19. JOURNAL DE PHYSIQUE Colloque Cl, supplkment au no 4, Tome 38, Auril 1977, page Cl-303 MULTILAYER SINTERING OF MnZn FERRITES

    E-Print Network [OSTI]

    Boyer, Edmond

    SINTERING OF MnZn FERRITES IN CONTROLLED ATMOSPHERE M. I. ALAM, N. R. NAlR and T. V. RAMAMURTI Central dans la litterature que I'empilement depots de ferrites les uns sur les autres durant le traitement production des couches multiples d'echantillons de ferrite de Mn-Zn. On a utilise jusqu'a 10 couches d

  20. Atomic-Scale Spin-Polarized Scanning Tunneling Microscopy Applied To Mn3N2(010) Haiqiang Yang and Arthur R. Smith

    E-Print Network [OSTI]

    source effusion cell for Mn and a rf plasma source for N [5,6]. All STM imaging is performed at 300 K-centered tetragonal (fct) rock-salt type struc- ture. The bulk magnetic moments of the Mn atoms are FM within (001

  1. Quantum Critical Transition Amplifies Magnetoelastic Coupling in Mn[N(CN)2]2

    SciTech Connect (OSTI)

    Brinzari, T. V.; Chen, P.; Sun, Q.-C.; Liu, J.; Tung, L.-C.; Wang, Y.; Schlueter, J. A.; Singleton, J.; Manson, J. L.; Whangbo, M.-H.; Litvinchuk, A. P.; Musfeldt, J. L.

    2013-06-01T23:59:59.000Z

    We report the discovery of a magnetic quantum critical transition in Mn[N(CN)2]2 that drives the system from a canted antiferromagnetic state to the fully polarized state with amplified magnetoelastic coupling as an intrinsic part of the process. The local lattice distortions, revealed through systematic phonon frequency shifts, suggest a combined MnN6 octahedra distortion+counterrotation mechanism that reduces antiferromagnetic interactions and acts to accommodate the field-induced state. These findings deepen our understanding of magnetoelastic coupling near a magnetic quantum critical point and away from the static limit.

  2. Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment

    E-Print Network [OSTI]

    Trassinelli, Martino; Eddrief, M; Etgens, V H; Gafton, V; Hidki, S; Lacaze, Emmanuelle; Lamour, Emily; Prigent, Christophe; Rozet, Jean-Pierre; Steydli, S; Zheng, Y; Vernhet, Dominique

    2014-01-01T23:59:59.000Z

    We present the investigation on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow highly charged ions bombardment under well-controlled conditions. The ion-induced defects facilitate the nucleation of one phase with respect to the other in the first-order magneto-structural MnAs transition with a consequent suppression of thermal hysteresis without any significant perturbation on the other structural and magnetic properties. In particular, the irradiated film keeps the giant magnetocaloric effect at room temperature opening new perspective on magnetic refrigeration technology for everyday use.

  3. Thermochemical generation of hydrogen and oxygen from water. [NaMnO/sub 2/ and TiO/sub 2/

    DOE Patents [OSTI]

    Robinson, P.R.; Bamberger, C.E.

    1980-02-08T23:59:59.000Z

    A thermochemical cyclic process for the production of hydrogen exploits the reaction between sodium manganate (NaMnO/sub 2/) and titanium dioxide (TiO/sub 2/) to form sodium titanate (Na/sub 2/TiO/sub 3/), manganese (II) titanate (MnTiO/sub 3/) and oxygen. The titanate mixture is treated with sodium hydroxide, in the presence of steam, to form sodium titanate, sodium manganate (III), water and hydrogen. The sodium titanate-manganate (III) mixture is treated with water to form sodium manganate (III), titanium dioxide and sodium hydroxide. Sodium manganate (III) and titanium dioxide are recycled following dissolution of sodium hydroxide in water.

  4. Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment

    SciTech Connect (OSTI)

    Trassinelli, M., E-mail: martino.trassinelli@insp.jussieu.fr; Marangolo, M.; Eddrief, M.; Etgens, V. H.; Gafton, V.; Hidki, S.; Lacaze, E.; Lamour, E.; Prigent, C.; Rozet, J.-P.; Steydli, S.; Zheng, Y.; Vernhet, D. [CNRS, UMR 7588, Institut des NanoSciences de Paris (INSP), F-75005 Paris (France); Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, F-75005 Paris (France)

    2014-02-24T23:59:59.000Z

    We present the investigation on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow highly charged ions bombardment under well-controlled conditions. The ion-induced defects facilitate the nucleation of one phase with respect to the other in the first-order magneto-structural MnAs transition, with a consequent suppression of thermal hysteresis without any significant perturbation on the other structural and magnetic properties. In particular, the irradiated film keeps the giant magnetocaloric effect at room temperature opening new perspective on magnetic refrigeration technology for everyday use.

  5. Effects of Ti substitution on structural and magnetic properties of Zn–Mn ferrospinels

    SciTech Connect (OSTI)

    Patil, R.P., E-mail: raj_rbm_raj@yahoo.com [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Patil, N.M. [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Sasikala, R. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Hankare, P.P., E-mail: p_hankarep@rediffmail.com [Department of Chemistry, Shivaji University, Kolhapur 416004 (India); Delekar, S.D. [Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Sub-campus Osmanabad, 413501 (India)

    2013-05-15T23:59:59.000Z

    Highlights: ? Novel system ZnMn{sub 1?x}Ti{sub x}FeO{sub 4} synthesized by sol–gel route. ? Nanocrystalline materials. ? Magnetic materials. - Abstract: Nanocrystalline ZnMn{sub 1?x}Ti{sub x}FeO{sub 4} (1.0 ? x ? 0) ferrites were prepared by sol–gel route. Formation of single phase cubic spinel structure for all the compositions was confirmed from their X-ray diffraction patterns. The lattice parameter shows an increasing trend with the increase in Ti content. These ferrite samples existed as crystalline nanoparticles of about 30–40 nm size as observed from transmission electron microscopy (TEM) technique. EDAX analysis indicated that the concentration of different elements in different compositions is in close agreement with the starting concentrations. Infrared spectra showed two main absorption bands in the range 400–800 cm{sup ?1} arising due to tetrahedral (A) and octahedral (B) stretching vibrations. The magnetic studies indicated that, the ferrimagnetic behavior increases with titanium substitution.

  6. Pulse Electrodeposition of Cu-ZnO and Mn-Cu-ZnO Nanowires

    SciTech Connect (OSTI)

    Gupta, Mayank; Pinisetty, D.; Flake, John C.; Spivey, James J.

    2010-01-01T23:59:59.000Z

    Cu–ZnO and Mn–Cu–ZnO nanowires are attractive catalysts for alcohol synthesis from CO hydrogenation reactions. Nanowire alloys are pulse electrodeposited into track etched polycarbonate membranes using aqueous electrolytes including Mn(NO{sub 3} ){sub 2} , Cu(NO{sub 3} ){sub 2} , Zn(NO{sub 3} ){sub 2} , and NH{sub 4} NO{sub 3} . Pulse waveforms with a cathodic current density of 50.7mAcm{sup ?2} for 50 ms (on-time), with varying off-times (400, 500, and 600 ms), are used to fabricate nanowire arrays (400 nm diameter, 25?m long, and pore density of 1.5×10{sup 8} pores cm{sup ?2} ). Pulse waveforms allow significantly higher copper concentrations and better control of zinc and manganese concentrations within nanowires. X-ray diffraction results show preferential growth in the (111) direction and crystallite size increases with an increase in off-time. Waveforms with longer off-times (500 and 600 ms) resulted in nanowires with relatively higher copper concentrations due to improved copper transport in nanopores. The nanowire surface has no manganese; however, the core shows manganese, which increases with the decrease in off-time. The effect of deposition conditions and electrolyte composition on nanowire properties are explained and discussed.

  7. Durability of (Pr0.7sr0.3)Mn03 +/-delta/8ysz

    SciTech Connect (OSTI)

    An, Ke [ORNL; Reifsnider, K L [University of Connecticut, Storrs; Gao, C Y [University of Tennessee, Knoxville (UTK)

    2006-01-01T23:59:59.000Z

    Half cell SOFCs with Durability of (Pr{sub 0.7}Sr{sub 0.3})Mn0{sub 3}{+-}{delta}/8YSZ composite cathodes on 8YSZ electrolytes were aged up to 1000 h at 1000 C in air with/without 0.318 A cm{sup -2} cathodic polarization. During the aging, the performance of the half cell SOFCs was measured using electrochemical impedance spectroscopy (EIS). After aging, the surface of the composite cathode and the interface between the composite cathode and the electrolyte was investigated with scanning electron microscopy (SEM). Chemical element analysis was performed with energy dispersive X-ray spectroscopy (EDS). The performance of the half cell SOFCs degraded after aging with/without polarization compared to the initial state. The SOFCs had a larger polarization resistance after 1000 h of aging. The cathodic current was shown to have an impact on the performance by slowing down the rate of decrease of polarization resistance of the SOFCs. After aging, the microstructural properties--mean pore size increased and cumulative pore volume decreased, and growth of grains was found on the Durability of (Pr{sub 0.7}Sr{sub 0.3})Mn0{sub 3}{+-}{delta} phases.

  8. Microstructure and Magnetic Properties of PrMnO{sub 3} Bulk and Thin Film

    SciTech Connect (OSTI)

    Lim, K. P.; Halim, S. A.; Chen, S. K.; Ng, S. W.; Wong, J. K.; Gan, H. M. Albert [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Woon, H. S. [College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, 43000 Kajang, Selangor (Malaysia)

    2011-03-30T23:59:59.000Z

    Perovskite PrMnO{sub 3}(PMO) had been prepared in bulk by solid state reaction and thin films on corning glass, fused silica and MgO (100) glass substrate by pulsed laser deposition technique. SEM micrographs show that grains with size 2{approx}3 {mu}m is observed in bulk PMO while thin films PMO show strongly connected grain structure with particle size that not larger than 100 nm. X-ray diffraction analysis shows that all samples are in single phase with orthorhombic crystal structure. Bulk PMO sample had lattice strain of 0.134% which is the lowest value among others. However, larger lattice strain was observed in thin film samples due to lattice mismatch between film-substrate and caused the MnO{sub 6} to deform. All samples shown paramagnetic or antiferromagnetic behavior, enhancement in magnetization value occurred for all PMO grew as film. We believe that larger lattice strain favor the grain growth of PMO towards more order phase. In summary, formation of structure and microstructure of thin film PMO depends on type of substrate used and it affect the magnetic property.

  9. Electrochemically induced deposition method to prepare {gamma}-MnO{sub 2}/multi-walled carbon nanotube composites as electrode material in supercapacitors

    SciTech Connect (OSTI)

    Fan Zhen [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Chen Jinhua [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)], E-mail: chenjinhua@hnu.cn; Zhang Bing; Sun Feng; Liu Bo; Kuang Yafei [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2008-08-04T23:59:59.000Z

    The {gamma}-MnO{sub 2}/multi-walled carbon nanotube ({gamma}-MnO{sub 2}/MWNT) composite has been prepared by electrochemically induced deposition method. The morphology and crystal structure of the composite were investigated by X-ray diffraction and scanning electron microscopy, respectively. The capacitive properties of the {gamma}-MnO{sub 2}/MWNT composite have been investigated by cyclic voltammetry (CV). A specific capacitance (based on {gamma}-MnO{sub 2}) as high as 579 F g{sup -1} is obtained at a scan rate of 10 mV s{sup -1} in 0.1 M Na{sub 2}SO{sub 4} aqueous solution. Additionally, the {gamma}-MnO{sub 2}/MWNT composite electrode shows excellent long-term cycle stability (only 2.4% decrease of the specific capacitance is observed after 500 CV cycles)

  10. Radiation-induced instability of MnS precipitates and its possible consequences on irradiation-induced stress corrosion cracking of austenitic stainless steels

    SciTech Connect (OSTI)

    Chung, H.M.; Sanecki, J.E. [Argonne National Lab., IL (United States); Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-01T23:59:59.000Z

    Irradiation-assisted stress corrosion cracking (IASCC) is a significant materials issue for the light water reactor (LWR) industry and may also pose a problem for fusion power reactors that will use water as coolant. A new metallurgical process is proposed that involves the radiation-induced release into solution of minor impurity elements not usually thought to participate in IASCC. MnS-type precipitates, which contain most of the sulfur in stainless steels, are thought to be unstable under irradiation. First, Mn transmutes strongly to Fe in thermalized neutron spectra. Second, cascade-induced disordering and the inverse Kirkendall effect operating at the incoherent interfaces of MnS precipitates are thought to act as a pump to export Mn from the precipitate into the alloy matrix. Both of these processes will most likely allow sulfur, which is known to exert a deleterious influence on intergranular cracking, to re-enter the matrix. To test this hypothesis, compositions of MnS-type precipitates contained in several unirradiated and irradiated heats of Type 304, 316, and 348 stainless steels (SSs) were analyzed by Auger electron spectroscopy. Evidence is presented that shows a progressive compositional modification of MnS precipitates as exposure to neutrons increases in boiling water reactors. As the fluence increases, the Mn level in MnS decreases, whereas the Fe level increases. The S level also decreases relative to the combined level of Mn and Fe. MnS precipitates were also found to be a reservoir of other deleterious impurities such as F and O which could be also released due to radiation-induced instability of the precipitates.

  11. From 1D Chain to 3D Network: Syntheses, Structures, and Properties of K2MnSn2Se6, K2MnSnSe4, and

    E-Print Network [OSTI]

    Li, Jing

    and MnSe4 tetrahedra, with large channels hosting the K+ cations. III is a layered compound containing 2 tetrahedra into two-dimensional (2D) sheets.1 The 1D 1 [SnQ3]2- rib- bons have also been observed- rahedra to Ag atoms, with large channels hosting the K+ cations.4 In this paper, we report the preparation

  12. Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

    SciTech Connect (OSTI)

    Maniraj, M [UGC-DAE Confortium for Scientific Research; Rai, Abhishek [UGC-DAE Confortium for Scientific Research; Barman, S R [UGC-DAE Confortium for Scientific Research; Krajci, M [Slovak Academy of Sciences; Schlagel, Deborah L [Ames Laboratory; Lograsso, Thomas A [Ames Laboratory; Horn, K [Fritz-Haber-Institut der Max-Planck-Gesellschaft

    2014-09-01T23:59:59.000Z

    We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15±0.1)me and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows an absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i?Al?Pd?Mn as predicted by density functional theory calculations, and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i?Al?Pd?Mn with the free-electron-like image potential states. Our investigation of the energy region immediately above EF provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations.

  13. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    SciTech Connect (OSTI)

    Pramanick, S.; Giri, S.; Majumdar, S., E-mail: sspsm2@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A and B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India); Chatterjee, S. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, Sector III, LB-8, Salt Lake, Kolkata 700 098 (India)

    2014-09-15T23:59:59.000Z

    Present work reports on the observation of large magnetoresistance (??30% at 80 kOe) and magnetocaloric effect (?12?J·kg{sup ?1}·K{sup ?1} for 0–50 kOe) near room temperature (?290?K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288?K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  14. Unusual magnetic hysteresis and the weakened transition behavior induced by Sn substitution in Mn{sub 3}SbN

    SciTech Connect (OSTI)

    Sun, Ying, E-mail: sunying@buaa.edu.cn [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Guo, Yanfeng; Li, Jun; Wang, Xia [Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Tsujimoto, Yoshihiro [Materials Processing Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Wang, Cong [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); Feng, Hai L.; Sathish, Clastin I.; Yamaura, Kazunari, E-mail: yamaura.kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Matsushita, Yoshitaka [Analysis Station, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-01-28T23:59:59.000Z

    Substitution of Sb with Sn was achieved in ferrimagnetic antiperovskite Mn{sub 3}SbN. The experimental results indicate that with an increase in Sn concentration, the magnetization continuously decreases and the crystal structure of Mn{sub 3}Sb{sub 1-x}Sn{sub x}N changes from tetragonal to cubic phase at around x of 0.8. In the doping series, step-like anomaly in the isothermal magnetization was found and this behavior was highlighted at x?=?0.4. The anomaly could be attributed to the magnetic frustration, resulting from competition between the multiple spin configurations in the antiperovskite lattice. Meantime, H{sub c} of 18 kOe was observed at x?=?0.3, which is probably the highest among those of manganese antiperovskite materials reported so far. With increasing Sn content, the abrupt change of resistivity and the sharp peak of heat capacity in Mn{sub 3}SbN were gradually weakened. The crystal structure refinements indicate the weakened change at the magnetic transition is close related to the change of c/a ratio variation from tetragonal to cubic with Sn content. The results derived from this study indicate that the behavior of Mn{sub 3}Sb{sub 1-x}Sn{sub x}N could potentially enhance its scientific and technical applications, such as spin torque transfer and hard magnets.

  15. Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting

    E-Print Network [OSTI]

    Lee, Cin-Ty Aeolus

    Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn online 1 June 2011 Editor: L. Stixrude Keywords: transition metals mineralogical heterogeneities are sensitive to changes in mineralogy or major element composition, and thus, are promising to trace

  16. Iron-based soft magnetic composites with MnZn ferrite nanoparticles coating obtained by solgel method

    E-Print Network [OSTI]

    Volinsky, Alex A.

    ­gel method Shen Wu a , Aizhi Sun a,n , Wenhuan Xu a , Qian Zhang a , Fuqiang Zhai a , Philip Logan b , Alex A-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature

  17. A non-volatile-memory device on the basis of engineered anisotropies in (Ga,Mn)As

    E-Print Network [OSTI]

    Loss, Daniel

    ARTICLES A non-volatile-memory device on the basis of engineered anisotropies in (Ga,Mn)As KATRIN by Moore's law, the semiconductor industry will need to develop novel device concepts that go beyond simple Hall effect6 , tunnelling AMR (TAMR)7­9 and Coulomb blockade AMR10 . These previous demonstrations have

  18. Microstructure, mechanical property and corrosion behaviors of interpenetrating C/Mg-Zn-Mn composite fabricated by suction casting

    E-Print Network [OSTI]

    Zheng, Yufeng

    bonding between Mg-Zn-Mn alloy and carbon scaffold was very well. The composite had an ultimate. Introduction Carbon, in all its forms, such as carbon nanotubes, carbon fabric, carbon-carbon composites, glassy carbon, pyrocarbons and diamond- like layers, is considered as a promising material for biomedical

  19. Sidorenkite (Na3MnPO4CO3): A New Intercalation Cathode Material for Na-Ion Batteries

    E-Print Network [OSTI]

    Ceder, Gerbrand

    - 180 Wh/kg) than other rechargeable batteries, such as lead-acid and Ni-Cd batteries. Na-ion batteriesSidorenkite (Na3MnPO4CO3): A New Intercalation Cathode Material for Na-Ion Batteries Hailong Chen, Cambridge, United Kingdom *S Supporting Information ABSTRACT: Na-ion batteries represent an effective energy

  20. Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    temperature opening new perspective on magnetic refrigeration technology for everyday use. martino on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow and magnetic prop- erties. In particular, the irradiated film keeps the giant magnetocaloric effect at room

  1. Selective adsorption of manganese onto cobalt for optimized Mn/Co/TiO2 FischerTropsch catalysts

    E-Print Network [OSTI]

    Regalbuto, John R.

    Selective adsorption of manganese onto cobalt for optimized Mn/Co/TiO2 Fischer­Tropsch catalysts promotion Fischer­Tropsch Strong Electrostatic Adsorption a b s t r a c t The Strong Electrostatic Adsorption (SEA) method was applied to the rational design of a promoted Co catalyst for Fischer­Tropsch (FT

  2. Unraveling the voltage fade mechanism in layer Li-Mn-rich electrode: formation of the tetrahedral cations for spinel conversion

    SciTech Connect (OSTI)

    Mohanty, Debasish [ORNL; Li, Jianlin [ORNL; Abraham, Daniel P [Argonne National Laboratory (ANL); Huq, Ashfia [ORNL; Payzant, E Andrew [ORNL; Wood III, David L [ORNL; Daniel, Claus [ORNL

    2014-01-01T23:59:59.000Z

    Discovery of high-voltage layered lithium-and manganese-rich (LMR) composite oxide electrode has dramatically enhanced the energy density of current Li-ion energy storage systems. However, practical usage of these materials is currently not viable because of their inability to maintain a consistent voltage profile (voltage fading) during subsequent charge-discharge cycles. This report rationalizes the cause of this voltage fade by providing the evidence of layer to spinel-like (LSL) structural evolution pathways in the host Li1.2Mn0.55Ni0.15Co0.1O2 LMR composite oxide. By employing neutron powder diffraction, and temperature dependent magnetic susceptibility, we show that LSL structural rearrangement in LMR oxide occurs through a tetrahedral cation intermediate via: i) diffusion of lithium atoms from octahedral to tetrahedral sites of the lithium layer [(LiLioct LiLitet] which is followed by the dispersal of the lithium ions from the adjacent octahedral site of the metal layer to the tetrahedral sites of lithium layer [LiTM oct LiLitet]; and ii) migration of Mn from the octahedral sites of the transition metal layer to the permanent octahedral site of lithium layer via tetrahedral site of lithium layer [MnTMoct MnLitet MnLioct)]. The findings opens the door to the potential routes to mitigate this atomic restructuring in the high-voltage LMR composite oxide cathodes by manipulating the composition/structure for practical use in high-energy-density lithium-ion batteries.

  3. Facile synthesis of {alpha}-MnO{sub 2} one-dimensional (1D) nanostructure and energy storage ability studies

    SciTech Connect (OSTI)

    Yousefi, Taher, E-mail: anozadg@yahoo.com [Department of Chemistry, Tarbiat Moallem University, PO Box: 31979-37551, Tehran (Iran, Islamic Republic of); Materials Research School, NSTRI, PO Box: 14395-836, Tehran (Iran, Islamic Republic of); Golikand, Ahmad Nozad, E-mail: taher_yosefy@yahoo.com [Materials Research School, NSTRI, PO Box: 14395-836, Tehran (Iran, Islamic Republic of); Hossein Mashhadizadeh, Mohammad [Department of Chemistry, Tarbiat Moallem University, PO Box: 31979-37551, Tehran (Iran, Islamic Republic of); Aghazadeh, Mustafa [Department of Optic and Spectroscopy, Lasers and Optics Research School, NSTRI, PO Box: 11365-8486, Tehran (Iran, Islamic Republic of)

    2012-06-15T23:59:59.000Z

    The dense manganese oxide nanorods with an extremely narrow distribution are synthesized at a low temperature using first cathodic electrodeposition subsequently heat treatment. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that the nanorods have bar shapes, and their average diameter is less than 50 nm. The Fourier transform infrared (FT-IR) study, the selected area electron diffraction (SAED) pattern in TEM images and the X-ray diffraction (XRD) result show that the nanorods are {alpha}-MnO{sub 2} single crystal. The results of N{sub 2} adsorption-desorption analysis indicate that the BET surface area of the {alpha}-MnO{sub 2} nanorods is 93 m{sup 2} g{sup -1}. By recording the potential-time curve during the electrodeposition process, it is revealed that water reduction reaction has a major role in the electrogeneration of base at the cathode surface under the applied electrochemical conditions. Finally, based on the H{sub 2} bubbling on the cathode surface, the mechanism of the formation and the growth of {alpha}-MnO{sub 2} nanorods are proposed and discussed. For the electrochemical supercapacitor application, electrochemically prepared {alpha}-MnO{sub 2} is found to be stable for a large number of cycles with high specific capacitance, 338 F g{sup -1} at a scan rate of 10 mV s{sup -1}. Finally, the charge-discharge mechanism is discussed. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer New nanostructures of MnO{sub 2} is synthesized by simple method of cathodicelectrodeposition. Black-Right-Pointing-Pointer The product has unique one-dimensional morphology with average diameter size of 50 nm. Black-Right-Pointing-Pointer The experiment conditions (temperature, current density) has not been reported. Black-Right-Pointing-Pointer The one-nanostructures obtained without using of hard template or surfactant.

  4. Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region

    SciTech Connect (OSTI)

    Pigni,M.T.; Herman, M.; Oblozinsky, P.

    2008-06-24T23:59:59.000Z

    We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from keV range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.

  5. Angular dependence of the magnetization reversal in exchangebiased Fe/MnF2

    SciTech Connect (OSTI)

    Arenholz, Elke; Liu, Kai

    2005-05-01T23:59:59.000Z

    A detailed study of exchange-biased Fe/MnF{sub 2} bilayers using magneto-optical Kerr Effect shows that the magnetization reversal occurs almost fully through domain wall nucleation and propagation for external fields parallel to the exchange bias direction. For finite angles {phi} between bias and external field the magnetization is aligned perpendicular to the field cooling direction for a limited field range for decreasing fields. For external fields perpendicular to the bias direction the magnetization aligns with the field cooling direction for descending and ascending fields before fully reversing. The field range for which the magnetization is close to perpendicular to the external field can be estimated using a simple effective field model.

  6. Magnetic-field-induced transformation in FeMnGa alloys

    SciTech Connect (OSTI)

    Zhu, W.; Liu, E. K.; Feng, L.; Tang, X. D.; Chen, J. L.; Wu, G. H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, H. Y.; Meng, F. B.; Luo, H. Z. [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2009-11-30T23:59:59.000Z

    A kind of ferromagnetic shape memory alloy with off-stoichiometric composition of Heusler alloy Fe{sub 2}MnGa has been synthesized. By optimizing composition, the martensitic transformation has been modified to occur at about 163 K accompanying spontaneous magnetization, which enables a magnetic field-induced structural transition from a paramagnetic parent phase to a ferromagnetic martensite with high magnetization of 93.8 emu/g. The material performs a quite large lattice distortion through the transformation, (c-a)/c=33.5%, causing a shape memory strain upto 3.6%. Such large lattice distortions strongly influence the electron structures, and thus some special physical behavior related to the transport and conductive properties is investigated.

  7. Structural controlled magnetic anisotropy in Heusler L1{sub 0}-MnGa epitaxial thin films

    SciTech Connect (OSTI)

    Wang Kangkang; Lu Erdong; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Knepper, Jacob W.; Yang Fengyuan [Department of Physics, Ohio State University, 191 Woodruff Ave., Columbus, Ohio 43210 (United States)

    2011-04-18T23:59:59.000Z

    Ferromagnetic L1{sub 0}-MnGa thin films have been epitaxially grown on GaN, sapphire, and MgO substrates using molecular beam epitaxy. Using diffraction techniques, the epitaxial relationships are determined. It is found that the crystalline orientation of the films differ due to the influence of the substrate. By comparing the magnetic anisotropy to the structural properties, a clear correlation could be established indicating that the in-plane and out-of-plane anisotropy is directly determined by the crystal orientation of the film and could be controlled via selection of the substrates. This result could be helpful in tailoring magnetic anisotropy in thin films for spintronic applications.

  8. Isovector pairing in odd-odd N=Z {sup 50}Mn.

    SciTech Connect (OSTI)

    O'Leary, C. D. O.; Bentley, M. A.; Lenzi, S. M.; Martinez-Pinedo, G.; Warner, D. D.; Bruce, A. M.; Cameron, J. A.; Carpenter, M. P.; Davids, C. N.; Fallon, P.; Frankland, L.; Gelletly, W.; Janssens, R. V. F.; Joss, D. T.; Lister, C. J.; Regan, P. H.; Reiter, P.; Rubio, B.; Seweryniak, D.; Svensson, C. E.; Vincent, S. M.; Williams, S. J.; Physics; Univ. of York; Univ. of Liverpool; Keele Univ.; Dipartimento di Fisica dell'Universit and INFN; Univ. Basel; CLRC Daresbury Lab.; Univ. of Brighton; McMaster Univ.; LBNL; Univ. of Surrey; CSIC-Uni.

    2002-01-17T23:59:59.000Z

    High-spin states in the odd-odd N=Z nucleus {sup 50}{sub 25}Mn have been investigated. A sequence of states up to J{sup {pi}}=6{sup +} has been assigned as the T=1 analogue of the yrast band in {sup 50}{sub 24}Cr for the first time. The differences in energy between levels in these bands are interpreted in terms of rotational alignments and the effect they have on the Coulomb energy of the nucleus. Comparisons with shell model calculations show that the Coulomb energy difference between the T=1 analogue structures is an important indicator of the competition between isovector pairing modes in N=Z nuclei and their isobars.

  9. Mirror symmetry at high spin in {sup 51}Fe and {sup 51}Mn

    SciTech Connect (OSTI)

    Bentley, M. A.; Williams, S. J.; Joss, D. T.; O'Leary, C. D.; Bruce, A. M.; Cameron, J. A.; Carpenter, M. P.; Fallon, P.; Frankland, L.; Gelletly, W. (and others)

    2000-11-01T23:59:59.000Z

    Gamma decays from excited states in the T{sub z}=-1/2 nucleus {sup 51}Fe have been observed for the first time. The differences in excitation energies as compared with those of the mirror partner, {sup 51}Mn, have been interpreted in terms of Coulomb effects and the resulting Coulomb energy differences (CED) can be understood intuitively in terms of particle-alignment effects. A new CED effect has been observed, in which different CED trends have been measured for each signature of the rotational structures that characterize these mid-f{sub 7/2} shell nuclei. Large-scale fp-shell model calculations have been used to compute the trends of the CED as a function of spin. The result of comparing these calculations with the data demonstrates an ability to reproduce the fine details of the Coulomb effects with a precision far greater than has been previously achieved.

  10. Effect of CoFe insertion in Co{sub 2}MnSi/CoFe/n-GaAs junctions on spin injection properties

    SciTech Connect (OSTI)

    Ebina, Yuya; Akiho, Takafumi; Liu, Hong-xi; Yamamoto, Masafumi; Uemura, Tetsuya, E-mail: uemura@ist.hokudai.ac.jp [Division of Electronics for Informatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan)

    2014-04-28T23:59:59.000Z

    The CoFe thickness (t{sub CoFe}) dependence of spin injection efficiency was investigated for Co{sub 2}MnSi/CoFe/n-GaAs junctions. The ?V{sub NL}/I value, which is a measure of spin injection efficiency, strongly depended on t{sub CoFe}, where ?V{sub NL} is the amplitude of a nonlocal spin-valve signal, and I is an injection current. Importantly, the maximum value of ?V{sub NL}/I for a Co{sub 2}MnSi/CoFe/n-GaAs junction was one order of magnitude higher than that for a CoFe/n-GaAs junction, indicating that a Co{sub 2}MnSi electrode works as a highly polarized spin source. No clear spin signal, on the other hand, was observed for a Co{sub 2}MnSi/n-GaAs junction due to diffusion of Mn atoms into the GaAs channel. Secondary ion mass spectrometry analysis indicated that the CoFe insertion effectively suppressed the diffusion of Mn into GaAs, resulting in improved spin injection properties compared with those for a Co{sub 2}MnSi/n-GaAs junction.

  11. Magneto-transport in LaTi{sub 1?x}Mn{sub x}O{sub 3}/SrTiO{sub 3} oxide heterostructures

    SciTech Connect (OSTI)

    Kumar, Pramod, E-mail: pramodnpl2011@gmail.com; Dogra, Anjana, E-mail: pramodnpl2011@gmail.com; Budhani, R. C., E-mail: pramodnpl2011@gmail.com [Quantum Phenomena and Applications Division, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Marg, New Delhi-110012 (India)

    2014-04-24T23:59:59.000Z

    We report the growth of ultrathin film of Mn doped LaTiO{sub 3} on TiO{sub 2} terminated SrTiO{sub 3} (001) substrate by pulsed laser deposition (PLD) and their electrical transport characteristics including magnetoresistance (MR). Though the replacement of Mn in LaTiO{sub 3} at the Ti site in dilute limit does not affect the metallic behaviour of films but variation in resistance is observed. Normalised resistance behaviour is explained on the basis of variation in charge carriers and increased interaction between Mn atoms in the system under investigation.

  12. Atomic moments in Mn2CoAl thin films analyzed by X-ray magnetic circular dichroism

    SciTech Connect (OSTI)

    Jamer, M. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics; Sterbinsky, G. [Brookhaven National Laboratory (BNL), Upton, NY (United States). Photon Sciences Directorate; Assaf, B. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics; Arena, D. [Brookhaven National Laboratory (BNL), Upton, NY (United States). Photon Sciences Directorate; Heiman, D. [Northwestern Univ., Evanston, IL (United States). Dept. of Physics

    2014-12-07T23:59:59.000Z

    Spin gapless semiconductors are known to be strongly affected by structural disorder when grown epitaxially as thin films. The magnetic properties of Mn2CoAl thin films grown on GaAs (001) substrates are investigated here as a function of annealing. This study investigates the atomic-specific magnetic moments of Mn and Co atoms measured through X-ray magnetic circular dichroism as a function of annealing and the consequent structural ordering. The results indicate that the structural distortion mainly affects the Mn atoms as seen by the reduction of the magnetic moment from its predicted value. (auth)

  13. In Second International Workshop on Security and Privacy in Cloud Computing, Minneapolis, MN. 24 June 2011. Private Editing Using Untrusted Cloud Services

    E-Print Network [OSTI]

    Evans, David

    In Second International Workshop on Security and Privacy in Cloud Computing, Minneapolis, MN. 24 of Virginia MightBeEvil.com Abstract--We present a general methodology for protecting the confidentiality

  14. Effect of ball milling and post-annealing on magnetic properties of Ni49.8Mn28.5Ga21.7 alloy powders

    E-Print Network [OSTI]

    Zheng, Yufeng

    , The University of Western Australia, Crawley WA6009, Australia c Department of Advanced Materials mechanical energy absorption [8,9]. Ni­Mn­Ga powders have been prepared by various methods, including spark

  15. Combustion Synthesis of Nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1, 0.2) Carbon Composites

    E-Print Network [OSTI]

    Doeff, Marca M

    2010-01-01T23:59:59.000Z

    G. J. Exarhos: Glycine-nitrate Combustion Synthesis of Oxideby the Nitrate-Citrate Combustion Method. Mat. Res. Bull.Combustion Synthesis of Nanoparticulate LiMg x Mn 1-x PO 4 (

  16. Bicolor Mn-doped CuInS{sub 2}/ZnS core/shell nanocrystals for white light-emitting diode with high color rendering index

    SciTech Connect (OSTI)

    Huang, Bo; Dai, Qian; Zhang, Huichao; Liao, Chen; Cui, Yiping; Zhang, Jiayu, E-mail: jyzhang@seu.edu.cn [Advanced Photonic Center, Southeast University, Nanjing 210096 (China); Zhuo, Ningze; Jiang, Qingsong; Shi, Fenghua; Wang, Haibo [Research Institute of Electric Light Source Materials, Nanjing University of Technology, Nanjing 210015 (China)

    2014-09-07T23:59:59.000Z

    We synthesized bicolor Mn-doped CuInS{sub 2} (CIS)/ZnS core/shell nanocrystals (NCs), in which Mn{sup 2+} ions and the CIS core were separated with a ZnS layer, and both Mn{sup 2+} ions and CIS cores could emit simultaneously. Transmission electron microscopy and powder X-ray diffraction measurements indicated the epitaxial growth of ZnS shell on the CuInS{sub 2} core, and electron paramagnetic resonance spectrum indicated that Mn{sup 2+} ions were on the lattice points of ZnS shell. By integrating these bicolor NCs with commercial InGaN-based blue-emitting diodes, tricolor white light-emitting diodes with color rendering index of 83 were obtained.

  17. Valence-state Model of Strain-dependent Mn L2,3 X-ray Magnetic Circular Dichroism from Ferromagnetic Semiconductors

    SciTech Connect (OSTI)

    van der Laan, G.; Edmonds, K. W.; Arenholz, E.; Farley, N. R. S.; Gallagher, B. L.

    2010-03-30T23:59:59.000Z

    We present a valence-state model to explain the characteristics of a recently observed pre-edge feature in Mn L{sub 3} x-ray magnetic circular dichroism (XMCD) of ferromagnetic (Ga,Mn)As and (Al,Ga,Mn)As thin films. The prepeak XMCD shows a uniaxial anisotropy, contrary to the cubic symmetry of the main structures induced by the crystalline electric field. Reversing the strain in the host lattice reverses the sign of the uniaxial anisotropy. With increasing carrier localization, the prepeak height increases, indicating an increasing 3d character of the hybridized holes. Hence, the feature is ascribed to transitions from the Mn 2p core level to unoccupied p-d hybridized valence states. The characteristics of the prepeak are readily reproduced by the model calculation taking into account the symmetry of the strain-, spin-orbit-, and exchange-split valence states around the zone center.

  18. Magnetic behavior of LaMn{sub 2}(Si{sub (1?x)}Ge{sub x}){sub 2} compounds characterized by magnetic hyperfine field measurements

    SciTech Connect (OSTI)

    Bosch-Santos, B., E-mail: brianna@usp.br; Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N. [Instituto de Pesquisas Energéticas e Nucleares, University of São Paulo, 05508-000 São Paulo (Brazil)

    2014-05-07T23:59:59.000Z

    The temperature dependence of the magnetic hyperfine field (B{sub hf}) at Mn atom sites was measured in LaMn{sub 2}(Si{sub (1?x)}Ge{sub x}){sub 2}, with 0???x???1, compounds with perturbed ??? angular correlation spectroscopy using {sup 111}In({sup 111}Cd) as probe nuclei in the temperature range from 20?K to 480?K. The results show a transition from antiferromagnetic to ferromagnetic ordering for all studied compounds when Ge gradually replaces Si and allowed an accurate determination of the Néel temperature (T{sub N}) for each compound. It was observed that T{sub N} decreases when Ge concentration increases. Conversely, the Curie temperature increases with increase of Ge concentration. This remarkable change in the behavior of the transition temperatures is discussed in terms of the Mn-Mn distance and ascribed to a change in the exchange constant J{sub ex}.

  19. Room-temperature photomagnetism in the spinel ferrite (Mn,Zn,Fe)3O4 as seen via soft x-ray magnetic circular dichroism

    E-Print Network [OSTI]

    Bettinger, J.S.

    2010-01-01T23:59:59.000Z

    photomagnetism in the spinel ferrite (Mn,Zn,Fe)3O4 as seendoped garnets 1 , doped spinel ferrites 2 , doped perovskiteIn the doped garnets and ferrites, the microscopic origin of

  20. Microstructure and ferroelectric properties of MnO2-doped bismuth-layer ,,Ca,Sr...Bi4Ti4O15 ceramics

    E-Print Network [OSTI]

    Cao, Wenwu

    microscopy and energy dispersion spectroscopy showed that the platelike grains in CSBTM ceramics become site. In the lead-zirconium-titanium- PZT and barium-titanium- BT based piezoelectric ceramics, MnO2

  1. X-ray and neutron scattering studies of the Rb?MnF? and Cu?â??õxMgx̳GeO? in an external magnetic field

    E-Print Network [OSTI]

    Christianson, Rebecca J. (Rebecca Jean), 1973-

    2001-01-01T23:59:59.000Z

    This thesis presents results of two scattering studies of low dimensional magnetic materials. The first is a neutron scattering study of Rb2MnF4, a nearly ideal two-dimensional square lattice Heisenberg antiferromagnet ...

  2. Mon. Not. R. Astron. Soc. 000, 1?? (2002) Printed 3 November 2011 (MN LATEX style file v2.2) A generalised porosity formalism for isotropic and

    E-Print Network [OSTI]

    Cohen, David

    the first X-ray line profiles computed directly from line-driven instability simulations using a 3-D patchMon. Not. R. Astron. Soc. 000, 1­?? (2002) Printed 3 November 2011 (MN LATEX style file v2

  3. Electroluminescence of InGaAs/GaAs quantum-size heterostructures with (III, Mn)V and Ni ferromagnetic injectors

    SciTech Connect (OSTI)

    Prokof'eva, M. M., E-mail: marinaprkfeva@rambler.ru [Lobachevsky State University (Russian Federation); Dorokhin, M. V.; Danilov, Yu. A.; Kudrin, A. V.; Vikhrova, O. V. [Lobachevsky State University of Nizhni Novgorod, Physicotechnical Research Institute (Russian Federation)

    2010-11-15T23:59:59.000Z

    Electroluminescence characteristics of light-emitting diodes based on InGaAs/GaAs quantum well heterostructures with an injector layer made of ferromagnetic metal (Ni), semimetal compound (MnSb), or magnetic semiconductor (InMnAs) were comparatively studied. The general feature is electroluminescence quenching as the spacer layer thickness between a quantum well and a magnetic injector decreases. It was found that the temperature dependence of the electroluminescence in diodes with Ni and MnSb is caused by thermal ejection of carriers from the quantum well; in diodes with InMnAs, it is caused by the temperature dependence of the carrier concentration in magnetic semiconductor and thermal ejection of carriers from the quantum well in the high-temperature region.

  4. Solvothermal synthesis of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanophosphor in water/diethylene glycol system

    SciTech Connect (OSTI)

    Takeshita, Satoru; Honda, Joji [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Isobe, Tetsuhiko, E-mail: isobe@applc.keio.ac.jp [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Sawayama, Tomohiro; Niikura, Seiji [SINLOIHI Company, Limited, 2-19-12 Dai, Kamakura 247-8550 (Japan)

    2012-05-15T23:59:59.000Z

    The influence of aging of the suspension containing the amorphous precusors on structural, compositional and photoluminescent properties is studied to understand the mechanism on the formation of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanoparticles during the solvothermal reaction in the water/diethylene glycol mixed solvent. Aging at 200 Degree-Sign C for 20 min forms the crystalline Zn{sub 2}GeO{sub 4} nanorods and then they grow up to {approx} 50 nm in mean length after aging for 240 min. Their interplanar spacing of (410) increases with increasing the aging time. The photoluminescence intensity corresponding to the d-d transition of Mn{sup 2+} increases with increasing the aging time up to 120 min, and then decreases after aging for 240 min. The photoluminescence lifetime decreases with increasing the aging time, indicating the locally concentrated Mn{sup 2+} ions. These results reveal that Mn{sup 2+} ions gradually replace Zn{sup 2+} ions near surface through repeating dissolusion and precipitation processes during prolonged aging after the complete crystallization of Zn{sub 2}GeO{sub 4}. - Graphical abstract: TEM images of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanoparticles aged at 200 Degree-Sign C for different aging times in the mixed solvent of water and diethylene glycol. Highlights: Black-Right-Pointing-Pointer Mechanism on formation of Zn{sub 2}GeO{sub 4}:Mn{sup 2+} nanophosphor under solvothermal condition. Black-Right-Pointing-Pointer Zn{sub 2}GeO{sub 4} nanorods crystallize via amorphous precursors. Black-Right-Pointing-Pointer Gradual substitution of Mn{sup 2+} during prolonged aging. Black-Right-Pointing-Pointer Such an inhomogeneous Mn{sup 2+} doping process results in concentration quenching.

  5. Electrochemical Properties of Nonstoichiometric LiNi0.5Mn1.5O4-Thin-Film Electrodes Prepared by Pulsed

    E-Print Network [OSTI]

    Ceder, Gerbrand

    by Pulsed Laser Deposition H. Xia,a Y. S. Meng,b, *,z L. Lu,a,c and G. Cedera,b, * a Advanced Materials-crystallized nonstoichiometric LiNi0.5Mn1.5O4- thin-film electrodes were prepared by pulsed laser deposition PLD . The charge groups have reported transition metal substituted spinel materials LiMxMn2-xO4, M Ni, Co, Cu, Cr, Fe, etc

  6. A new strategy to diminish the 4 V voltage plateau of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4}

    SciTech Connect (OSTI)

    Liu, Guoqiang, E-mail: liugq@smm.neu.edu.cn; Zhang, Lingxi; Sun, Lu; Wang, Lun

    2013-11-15T23:59:59.000Z

    Graphical abstract: The annealed sample LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} cannot eliminate the 4-V voltage plateau completely. The Mg-doped compound LiNi{sub 0.5}Mn{sub 1.45}Mg{sub 0.05}O{sub 4} can effectively diminish the 4 V voltage plateau during charge and discharge process. - Highlights: • Mg-doped compound LiNi{sub 0.5}Mn{sub 1.45}Mg{sub 0.05}O{sub 4} was prepared. • The 4 V voltage plateau in the charge–discharge curves of LiNi{sub 0.5}Mn{sub 1.45}Mg{sub 0.05}O{sub 4} was diminished. • Compound LiNi{sub 0.5}Mn{sub 1.45}Mg{sub 0.05}O{sub 4} exhibited good electrochemical properties. - Abstract: As for spinel LiNi{sub 0.5}Mn{sub 1.5}O{sub 4}, there is 4 V voltage plateau in the charge–discharge profiles. This voltage plateau can be reduced by an annealing process, however it is hard to avoid it completely. In this study, a new strategy of partial substitution for Mn by Mg is applied. There is no 4 V voltage plateau in the charge–discharge profiles of Mg-doped compound LiNi{sub 0.5}Mn{sub 1.45}Mg{sub 0.05}O{sub 4}. This compound exhibits good electrochemical properties which can be used as cathode material of lithium ion batteries. At 1 C rate, it can deliver a capacity of around 129 mAh g{sup ?1} and remain good cycle performance.

  7. Temperature dependence of magnetic properties of La0.7Sr0.3MnO3SrTiO3 thin films on silicon substrates

    E-Print Network [OSTI]

    Boyer, Edmond

    by a 20-nm-thick SrTiO3 001 buffer layer. X-ray diffraction and atomic force microscopy studies. INTRODUCTION Perovskite manganites RE 1-x AE xMnO3, where RE =rare earth and AE=alkaline earth formTemperature dependence of magnetic properties of La0.7Sr0.3MnO3Ã?SrTiO3 thin films on silicon

  8. Improved Hydrogen Storage Performance of MgH2-LiAlH4 Composite by Addition of MnFe2O4

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Improved Hydrogen Storage Performance of MgH2-LiAlH4 Composite by Addition of MnFe2O4 Qi Wan, Ping States *S Supporting Information ABSTRACT: The catalytic effects of MnFe2O4 nanoparticles on the hydrogen storage properties of MgH2-LiAlH4, prepared by ball milling, are studied for the first time. The hydrogen

  9. Temperature-induced martensite in magnetic shape memory Fe{sub 2}MnGa observed by photoemission electron microscopy

    SciTech Connect (OSTI)

    Jenkins, Catherine; Scholl, Andreas; Kainuma, R.; Elmers, Hans-Joachim; Omori, Toshihiro

    2012-01-18T23:59:59.000Z

    The magnetic domain structure in single crystals of a Heusler shape memory compound near the composition Fe{sub 2}MnGa was observed during phase transition by photoelectron emission microscopy at Beamline 11.0.1.1 of the Advanced Light Source. The behavior is comparable with recent observations of an adaptive martensite phase in prototype Ni{sub 2}MnGa, although the pinning in the recent work is an epitaxial interface and in this work the e#11;ective pinning plane is a boundary between martensitic variants that transform in a self-accommodating way from the single crystal austenite phase present at high temperatures. Temperature dependent observations of the twinning structure give information as to the coupling behavior between the magnetism and the structural evolution.

  10. Extended investigation of intermartensitic transitions in Ni-Mn-Ga magnetic shape memory alloys: A detailed phase diagram determination

    SciTech Connect (OSTI)

    Çakir, Asli; Aktürk, Selçuk [Mu?la Üniversitesi, Fizik Bölümü, 48000 Mu?la (Turkey); Righi, Lara [Dipartimento Chimica GIAF, Universita di Parma, Parco Area delle Scienze 17/A, 43010 Parma (Italy); Albertini, Franca [IMEM-CNR, Parco Area delle Scienze 37/A, 43010 Parma (Italy); Acet, Mehmet; Farle, Michael [Faculty of Physics and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, D-47048 Duisburg (Germany)

    2013-11-14T23:59:59.000Z

    Martensitic transitions in shape memory Ni-Mn-Ga Heusler alloys take place between a high temperature austenite and a low temperature martensite phase. However, intermartensitic transformations have also been encountered that occur from one martensite phase to another. To examine intermartensitic transitions in magnetic shape memory alloys in detail, we carried out temperature dependent magnetization, resistivity, and x-ray diffraction measurements to investigate the intermartensitic transition in Ni{sub 50}Mn{sub 50–x}Ga{sub x} in the composition range 12?x?25 at. %. Rietveld refined x-ray diffraction results are found to be consistent with magnetization and resistivity data. Depending on composition, we observe that intermartensitic transitions occur in the sequences 7M?L1{sub 0},?5M?7M, and 5M?7M?L1{sub 0} with decreasing temperature. The L1{sub 0} non-modulated structure is most stable at low temperature.

  11. Alternating magnetic anisotropy of Li 2 ( Li 1 - x T x ) N ( T = Mn , Fe , Co , and Ni )

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jesche, A.; Ke, L.; Jacobs, J. L.; Harmon, B.; Houk, R. S.; Canfield, P. C.

    2015-05-01T23:59:59.000Z

    Substantial amounts of the transition metals Mn, Fe, Co, and Ni can be substituted for Li in single crystalline Li?(Li1-xTx)N. Isothermal and temperature-dependent magnetization measurements reveal local magnetic moments with magnitudes significantly exceeding the spin-only value. The additional contributions stem from unquenched orbital moments that lead to rare-earth-like behavior of the magnetic properties. Accordingly, extremely large magnetic anisotropies have been found. Most notably, the magnetic anisotropy alternates as easy plane?easy axis?easy plane?easy axis when progressing from T = Mn ? Fe ? Co ? Ni. This behavior can be understood based on a perturbation approach in an analytical, single-ion model. The calculated magnetic anisotropies show surprisingly good agreement with the experiment and capture the basic features observed for the different transition metals.

  12. Alternating magnetic anisotropy of Li 2 ( Li 1 - x T x ) N ( T = Mn , Fe , Co , and Ni )

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jesche, A.; Ke, L.; Jacobs, J. L.; Harmon, B.; Houk, R. S.; Canfield, P. C.

    2015-05-01T23:59:59.000Z

    Substantial amounts of the transition metals Mn, Fe, Co, and Ni can be substituted for Li in single crystalline Li?(Li1-xTx)N. Isothermal and temperature-dependent magnetization measurements reveal local magnetic moments with magnitudes significantly exceeding the spin-only value. The additional contributions stem from unquenched orbital moments that lead to rare-earth-like behavior of the magnetic properties. Accordingly, extremely large magnetic anisotropies have been found. Most notably, the magnetic anisotropy alternates as easy plane?easy axis?easy plane?easy axis when progressing from T = Mn ? Fe ? Co ? Ni. This behavior can be understood based on a perturbation approach in an analytical, single-ion model.more »The calculated magnetic anisotropies show surprisingly good agreement with the experiment and capture the basic features observed for the different transition metals.« less

  13. Conditions for spin-gapless semiconducting behavior in Mn{sub 2}CoAl inverse Heusler compound

    SciTech Connect (OSTI)

    Galanakis, I., E-mail: galanakis@upatras.gr [Department of Materials Science, School of Natural Sciences, University of Patras, GR-26504 Patra (Greece); Özdo?an, K., E-mail: kozdogan@yildiz.edu.tr [Department of Physics, Yildiz Technical University, 34210 ?stanbul (Turkey); ?a??o?lu, E.; Blügel, S. [Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich (Germany)

    2014-03-07T23:59:59.000Z

    Employing ab initio electronic structure calculations, we investigate the conditions for spin-gapless semiconducting (SGS) behavior in the inverse Mn{sub 2}CoAl Heusler compound. We show that tetragonalization of the lattice, which can occur during films growth, keeps the SGS character of the perfect cubic compound. On the contrary, atomic swaps even between sites with different local symmetry destroy the SGS character giving rise to a half-metallic state. Furthermore, the occurrence of Co-surplus leads also to half-metallicity. Thus, we propose that in order to achieve SGS behavior during the growth of Mn{sub 2}CoAl (and similar SGS Heusler compounds) thin films, one should minimize the occurrence of defects, while small deformations of the lattice, due to the lattice mismatch with the substrate, do not play a crucial role.

  14. Magneto-transport properties of oriented Mn{sub 2}CoAl films sputtered on thermally oxidized Si substrates

    SciTech Connect (OSTI)

    Xu, G. Z.; Du, Y.; Zhang, X. M.; Liu, E. K.; Wang, W. H., E-mail: wenhong.wang@iphy.ac.cn; Wu, G. H. [State Key Laboratory for Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, H. G. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

    2014-06-16T23:59:59.000Z

    Spin gapless semiconductors are interesting family of materials by embracing both magnetism and semiconducting due to their unique band structure. Its potential application in future spintronics requires realization in thin film form. In this Letter, we report fabrication and transport properties of spin gapless Mn{sub 2}CoAl films prepared on thermally oxidized Si substrates by magnetron sputtering deposition. The films deposited at 673?K are well oriented to (001) direction and display a uniform-crystalline surface. Magnetotransport measurements on the oriented films reveal a semiconducting-like resistivity, small anomalous Hall conductivity, and linear magnetoresistance representative of the transport signatures of spin gapless semiconductors. The magnetic properties of the films have also been investigated and compared to that of bulk Mn{sub 2}CoAl, showing small discrepancy induced by the composition deviation.

  15. Structure and magnetism in strained Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy

    SciTech Connect (OSTI)

    Prestat, E. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Karlsruher Institut fuer Technologie (KIT), Laboratorium fuer Elektronenmikroskopie, D-76128 Karlsruhe (Germany); Barski, A.; Bellet-Amalric, E.; Morel, R.; Tainoff, D.; Jain, A.; Porret, C.; Bayle-Guillemaud, P.; Jamet, M. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Jacquot, J.-F. [INAC, SCIB, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2013-07-01T23:59:59.000Z

    In this letter, we study the structural and magnetic properties of Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy using X-ray diffraction, high resolution transmission electron microscopy, and superconducting quantum interference device. Like in Mn doped Ge films, Mn atoms diffuse during the growth and aggregate into vertically aligned Mn-rich nanocolumns of a few nanometers in diameter. Transmission electron microscopy observations in plane view clearly indicate that the Sn incorporation is not uniform with concentration in Mn rich vertical nanocolumns lower than the detection limit of electron energy loss spectroscopy. The matrix exhibits a GeSn solid solution while there is a Sn-rich GeSn shell around GeMn nanocolumns. The magnetization in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} layers is higher than in Ge{sub 1-x}Mn{sub x} films. This magnetic moment enhancement in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} is probably related to the modification of the electronic structure of Mn atoms in the nanocolumns by the Sn-rich shell, which is formed around the nanocolumns.

  16. Structural investigations on Co{sub 3-x}Mn{sub x}TeO{sub 6}; (0 < x ? 2); High temperature ferromagnetism and enhanced low temperature anti-ferromagnetism

    SciTech Connect (OSTI)

    Singh, Harishchandra; Sinha, A. K., E-mail: anil@rrcat.gov.in, E-mail: hng@rrcat.gov.in; Ghosh, Haranath, E-mail: anil@rrcat.gov.in, E-mail: hng@rrcat.gov.in; Singh, M. N. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore—452013 (India); Rajput, Parasmani [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai—400085 (India); Prajapat, C. L.; Singh, M. R.; Ravikumar, G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai—400085 (India)

    2014-08-21T23:59:59.000Z

    In the quest of materials with high temperature ferromagnetism and low temperature anti-ferromagnetism, we prepare Co{sub 3-x}Mn{sub x}TeO{sub 6}; (0?Mn concentration using Synchrotron X-ray diffraction (SXRD) and X-ray absorption near edge structure measurements in corroboration with magnetism are presented. Phase diagram obtained from Rietveld Refinement on SXRD data as a function of Mn concentration indicates doping disproportionate mixing of both monoclinic (C2/c) and rhombohedral (R 3{sup ¯}) structure for x?Mn-O) bond lengths for x???0.5. Co and Mn K-edge XANES spectra reveal that both Co and Mn are in mixed oxidation state, Co{sup 2+}/Mn{sup 2+} and Co{sup 3+}/Mn{sup 3+}. Relative ratios of Co{sup 3+}/Co{sup 2+} and Mn{sup 3+}/Mn{sup 2+} obtained using Linear combination fit decrease with increasing x (for x???0.5). These structural and spectroscopic evidences are used to provide possible interpretation of the observed paramagnetic to ferromagnetic transition at around 185?K followed by an enhanced antiferromagnetic transition ?45?K for x?=?0.5.

  17. Investigations of the electronic and magnetic structures of Co{sub 2}YGa (Y=Cr, Mn) Heusler alloys and their (100) surfaces

    SciTech Connect (OSTI)

    Hamad, Bothina, E-mail: b.hamad@ju.edu.jo [Physics Department, The University of Jordan, Amman-11942 (Jordan)

    2014-03-21T23:59:59.000Z

    Density functional theory calculations are performed to investigate the structural, electronic, and magnetic properties of bulk structures of Co{sub 2}YGa (Y?=?Cr, Mn) Heusler alloys and the surfaces along the (100) orientation. The bulk structures of both alloys show a ferromagnetic behavior with total magnetic moments of 3.03?{sub B} and 4.09?{sub B} and high spin polarizations of 99% and 67% for Co{sub 2}CrGa and Co{sub 2}MnGa, respectively. The surfaces are found to exhibit corrugations due to different relaxations of the surface atoms. For the case of Co{sub 2}CrGa, two surfaces preserve the half metallicity, namely those with Cr-Ga and Ga– terminations with high spin polarizations above 90%, whereas it dropped to about 50% for the other surfaces. However, the spin polarizations of Co-Co and Mn-Ga terminated surfaces remain close to that of bulk Co{sub 2}MnGa alloy, whereas it is suppressed down to 17% for Co– termination. The highest local magnetic moments are found to be 3.26??{sub B} and 4.11??{sub B} for Cr and Mn surface atoms in Cr-Ga and Mn– terminated surfaces, respectively.

  18. Crystallographic, magnetic, and electronic structures of ferromagnetic shape memory alloys Ni{sub 2}XGa (X=Mn,Fe,Co) from first-principles calculations

    SciTech Connect (OSTI)

    Bai, J. [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, 110004 Shenyang (China); LETAM, CNRS FRE 3143 (former UMR 7078), University of Metz, 57045 Metz (France); Raulot, J. M.; Zhang, Y. D.; Esling, C. [LETAM, CNRS FRE 3143 (former UMR 7078), University of Metz, 57045 Metz (France); Zhao, X.; Zuo, L. [Key Laboratory for Anisotropy and Texture of Materials (MOE), Northeastern University, 110004 Shenyang (China)

    2011-01-01T23:59:59.000Z

    The crystallographic, magnetic and electronic structures of the ferromagnetic shape memory alloys Ni{sub 2}XGa (X=Mn, Fe, and Co), are systematically investigated by means of the first-principles calculations within the framework of density functional theory using the VIENNA AB INITIO SOFTWARE PACKAGE. The lattice parameters of both austenitic and martensitic phases in Ni{sub 2}MnGa have been calculated. The formation energies of the cubic phase of Ni{sub 2}XGa are estimated, and show a destabilization tendency if Mn atom is substituted by Fe or Co. From Ni{sub 2}MnGa to Ni{sub 2}CoGa, the down spin total density of states (DOS) at Fermi level is gradually increasing, whereas that of the up spin part remains almost unchanged. This is the main origin of the difference of the magnetic moment in these alloys. The partial DOS is dominated by the Ni and Mn 3d states in the bonding region below E{sub F}. There are two bond types existing in Ni{sub 2}XGa: one is between neighboring Ni atoms in Ni{sub 2}MnGa; the other is between Ni and X atoms in Ni{sub 2}FeGa and Ni{sub 2}CoGa alloys.

  19. Nanometer-scale electrochemical patterning of LiMn2O4 surfaces by an atomic force microscope operating in air

    SciTech Connect (OSTI)

    Kostecki, Robert; Bonhomme, Frederic; Servant, Laurent; Argoul, Francoise; McLarnon, Frank

    2001-06-22T23:59:59.000Z

    Electrochemical nanometer-scale patterning of the surface of a conducting lithium manganese oxide (LiMn{sub 2}O{sub 4}) by scanning probe microscopy (SPM) was studied. The ability to produce nanometer-size patterns of chemically modified oxide or nanometer-sized alterations of the oxide morphology is demonstrated and discussed with reference to possible mechanisms. It is demonstrated that unlike the SPM-based surface oxidation of metals and semiconductors, the LiMn{sub 2}O{sub 4} surface is altered via electrochemically generated species. We show that a localized surface chemical change can be confined to a depth which depends on the oxide-tip voltage difference and ambient humidity. In situ Raman microscopy measurements of localized electrochemical reaction products suggest complex mechanisms of processes induced at the LiMn{sub 2}O{sub 4} surface, such as delithiation through Li-proton exchange and disproportionation of LiMn{sub 2}O{sub 4} to MnO{sub 2} and soluble Mn{sup 2+} species.

  20. Essential role of catalysts (Mn, Au, and Sn) in the vapor liquid solid growth kinematics of ZnS nanowires

    SciTech Connect (OSTI)

    Rehman, S.; Shehzad, M. A.; Hafeez, M.; Bhatti, A. S., E-mail: asbhatti@comsats.edu.pk [Center for Micro and Nano Devices (CMND), Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2014-01-14T23:59:59.000Z

    In this paper, we demonstrate that surface energy of the catalyst is a vital parameter for the growth rate, self doping of the self assembled nanowires synthesized by employing vapor liquid solid growth technique. The synthesis of ZnS nanowires was done by selectively using three different catalysts (Mn, Au, and Sn), where Au, is the most common catalyst, was used as a reference. The distinctive difference in the growth rate was due to the surface energy of the metal alloy droplet and the interface energies, as explained theoretically using thermodynamic approach. We have found that the activation energy of diffusion of (Zn, S) species in the catalyst droplet was low in Sn (0.41?eV for Zn and 0.13?eV for S) and high in Mn (1.79?eV for Zn and 0.61?eV for S) compared to Au (0.62?eV for Zn and 0.21?eV for S) catalyzed ZnS nanostructures. The thermodynamic calculations predicted the growth rates of Sn (7.5?nm/s) catalyzed nanowires was faster than Au (5.1?nm/s) and Mn (4.6?nm/s) catalyzed ZnS nanostructures, which were in agreement with the experimental results. Finally, the location of the catalyst as dopant in the grown nanostructure was predicted and compared with experimental observations.

  1. Design of Semiconducting Tetrahedral Mn 1 ? x Zn x O Alloys and Their Application to Solar Water Splitting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Peng, Haowei; Ndione, Paul F.; Ginley, David S.; Zakutayev, Andriy; Lany, Stephan

    2015-05-01T23:59:59.000Z

    Transition metal oxides play important roles as contact and electrode materials, but their use as active layers in solar energy conversion requires achieving semiconducting properties akin to those of conventional semiconductors like Si or GaAs. In particular, efficient bipolar carrier transport is a challenge in these materials. Based on the prediction that a tetrahedral polymorph of MnO should have such desirable semiconducting properties, and the possibility to overcome thermodynamic solubility limits by nonequilibrium thin-film growth, we exploit both structure-property and composition-structure relationships to design and realize novel wurtzite-structure Mn??xZnxO alloys. At Zn compositions above x ? 0.3, thin films ofmore »these alloys assume the tetrahedral wurtzite structure instead of the octahedral rocksalt structure of MnO, thereby enabling semiconductor properties that are unique among transition metal oxides, i.e., a band gap within the visible spectrum, a band-transport mechanism for both electron and hole carriers, electron doping, and a band lineup suitable for solar hydrogen generation. A proof of principle is provided by initial photo-electrocatalytic device measurements, corroborating, in particular, the predicted favorable hole-transport properties of these alloys.« less

  2. Synthesis of Mn{sub 2}O{sub 3} homogeneous core/hollow-shell structures with excellent adsorption performance

    SciTech Connect (OSTI)

    Cao Jie, E-mail: candj@mail.ustc.edu.cn [Anhui Provincial Key Lab of Photonics Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Mao Qinghe [Anhui Provincial Key Lab of Photonics Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Qian Yitai [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2012-07-15T23:59:59.000Z

    Large-scale Mn{sub 2}O{sub 3} homogeneous core/hollow-shell structures with cube-shaped and dumbbell-shaped morphologies have been synthesized trough a facile and low-cost method. The microscopy analyses indicate that the core-shell microcubes have an average edge length of 2.5 {mu}m with a shell thickness of about 150 nm, and the core-shell microdumbbells were formed with a length of about 3 {mu}m and shell thickness of about 160 nm. The possible formation mechanism was discussed on the basis of transmission electron microscopy observations. The novel homogeneous core/hollow-shell structures were found to exhibit excellent performance in wastewater treatment. - Graphical abstract: A simple method is described for fabrication of Mn{sub 2}O{sub 3} homogeneous core/hollow-shell structures and the as-prepared materials showed a good ability to remove an organic pollutant in waste water. Highlights: Black-Right-Pointing-Pointer The Mn{sub 2}O{sub 3} homogeneous core/hollow-shell structures were successfully prepared. Black-Right-Pointing-Pointer A simple and high yield method was employed to fabricate such novel structure. Black-Right-Pointing-Pointer The products showed a good ability to remove an organic pollutant in waste water.

  3. Determination of elastic properties of a MnO{sub 2} coating by surface acoustic wave velocity dispersion analysis

    SciTech Connect (OSTI)

    Sermeus, J.; Glorieux, C., E-mail: christ.glorieux@fys.kuleuven.be [Laboratory for Acoustics and Thermal Physics, KU Leuven, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Sinha, R.; Vereecken, P. M. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Center for Surface Chemistry and Catalysis, KU Leuven, University of Leuven, Kasteelpark Arenberg 23, B-3001 Leuven (Belgium); Vanstreels, K. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium)

    2014-07-14T23:59:59.000Z

    MnO{sub 2} is a material of interest in the development of high energy-density batteries, specifically as a coating material for internal 3D structures, thus ensuring rapid energy deployment. Its electrochemical properties have been mapped extensively, but there are, to the best of the authors' knowledge, no records of the elastic properties of thin film MnO{sub 2}. Impulsive stimulated thermal scattering (ISTS), also known as the heterodyne diffraction or transient grating technique, was used to determine the Young's modulus (E) and porosity (?) of a 500?nm thick MnO{sub 2} coating on a Si(001) substrate. ISTS is an all optical method that is able to excite and detect surface acoustic waves (SAWs) on opaque samples. From the measured SAW velocity dispersion, the Young's modulus and porosity were determined to be E?=?25?±?1?GPa and ?=42±1%, respectively. These values were confirmed by independent techniques and determined by a most-squares analysis of the carefully fitted SAW velocity dispersion. This study demonstrates the ability of the presented technique to determine the elastic parameters of a thin, porous film on an anisotropic substrate.

  4. Design of Semiconducting Tetrahedral Mn 1 ? x Zn x O Alloys and Their Application to Solar Water Splitting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Peng, Haowei; Ndione, Paul F.; Ginley, David S.; Zakutayev, Andriy; Lany, Stephan

    2015-05-01T23:59:59.000Z

    Transition metal oxides play important roles as contact and electrode materials, but their use as active layers in solar energy conversion requires achieving semiconducting properties akin to those of conventional semiconductors like Si or GaAs. In particular, efficient bipolar carrier transport is a challenge in these materials. Based on the prediction that a tetrahedral polymorph of MnO should have such desirable semiconducting properties, and the possibility to overcome thermodynamic solubility limits by nonequilibrium thin-film growth, we exploit both structure-property and composition-structure relationships to design and realize novel wurtzite-structure Mn??xZnxO alloys. At Zn compositions above x ? 0.3, thin films of these alloys assume the tetrahedral wurtzite structure instead of the octahedral rocksalt structure of MnO, thereby enabling semiconductor properties that are unique among transition metal oxides, i.e., a band gap within the visible spectrum, a band-transport mechanism for both electron and hole carriers, electron doping, and a band lineup suitable for solar hydrogen generation. A proof of principle is provided by initial photo-electrocatalytic device measurements, corroborating, in particular, the predicted favorable hole-transport properties of these alloys.

  5. Phase diagram and magnetocaloric effects in Ni{sub 50}Mn{sub 35}(In{sub 1?x}Cr{sub x}){sub 15} and (Mn{sub 1?x}Cr{sub x})NiGe{sub 1.05} alloys

    SciTech Connect (OSTI)

    Quetz, Abdiel, E-mail: anorve2002@yahoo.com; Muchharla, Baleeswaraiah; Dubenko, Igor; Talapatra, Saikat; Ali, Naushad [Southern Illinois University, Carbondale, Illinois 62901 (United States); Samanta, Tapas; Stadler, Shane [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2014-05-07T23:59:59.000Z

    The magnetocaloric and thermomagnetic properties of Ni{sub 50}Mn{sub 35}(In{sub 1?x}Cr{sub x}){sub 15} and (Mn{sub 1?x}Cr{sub x}) NiGe{sub 1.05} systems for 0???x???0.105 and 0???x???0.1, respectively, have been studied by x-ray diffraction, differential scanning calorimetry, and magnetization measurements. Partial substitution of Cr for Mn in (Mn{sub 1?x}Cr{sub x})NiGe{sub 1.05} results in a first order magnetostructural transition from a hexagonal paramagnetic to an orthorhombic paramagnetic phase near T{sub M}???380?K (for x?=?0.07). Partial substitution of Cr for In in Ni{sub 50}Mn{sub 35}(In{sub 1?x}Cr{sub x}){sub 15} shifts the magnetostructural transition to a higher temperature (T?=?T{sub M}???450?K) for x?=?0.1. Large magnetic entropy changes of ?S?=??12 (J/(kgK)) and ?S?=??11 (J/(kgK)), both for a magnetic field change of 5?T, were observed in the vicinity of T{sub M} for (Mn{sub 1?x}Cr{sub x})NiGe{sub 1.05} and Ni{sub 50}Mn{sub 35}(In{sub 1?x}Cr{sub x}){sub 15}, respectively.

  6. Setting temperature effect in polycrystalline exchange-biased IrMn/CoFe bilayers

    SciTech Connect (OSTI)

    Fernandez-Outon, L. E.; Araujo Filho, M. S.; Araujo, R. E.; Ardisson, J. D.; Macedo, W. A. A. [Laboratorio de Fisica Aplicada, Centro de Desenvolvimento da Tecnologia Nuclear, 31270-901 Belo Horizonte, MG (Brazil)

    2013-05-07T23:59:59.000Z

    We study the effect of atomic interdiffusion on the exchange bias of polycrystalline IrMn/({sup 57}Fe + CoFe) multilayers due to the thermal setting process of exchange coupling during field annealing. Depth-resolved {sup 57}Fe conversion electron Moessbauer spectroscopy was used to quantify atomic interdiffusion. Vibrating sample magnetometry was used to monitor the variation of exchange bias and magnetisation. It was found that interface sharpness is only affected above {approx}350 Degree-Sign C. Three different stages for the setting of exchange bias can be inferred from our results. At the lower setting temperatures (up to 350 Degree-Sign C), the effect of field annealing involves alignment of spins and interfacial coupling due to the setting of both antiferromagnetic (AF) bulk and interface without significant interdiffusion. At a second stage (350-450 Degree-Sign C), where AF ordering dominates over diffusion effects, atomic migration and increased setting of AF spins co-exist to produce a peak in exchange bias field and coercivity. On a third stage (>450 Degree-Sign C), severe chemical intermixing reduces significantly the F/AF coupling.

  7. Pressure-Induced Enhanced Magnetic Anisotropy in Mn(N(CN)2)2

    SciTech Connect (OSTI)

    Quintero, P. A. [University of Florida, Gainesville; Rajan, D. [University of Florida, Gainesville; Peprah, M. K. [University of Florida, Gainesville; Brinzari, T. V. [University of Florida, Gainesville; Fishman, Randy Scott [ORNL; Talham, Daniel R. [University of Florida, Gainesville; Meisel, Mark W. [University of Florida, Gainesville

    2015-01-01T23:59:59.000Z

    Using DC and AC magnetometry, the pressure dependence of the magnetization of the threedimensional antiferromagnetic coordination polymer Mn(N(CN)2)2 was studied up to 12 kbar and down to 8 K. The magnetic transition temperature, Tc, increases dramatically with applied pressure (P), where a change from Tc(P = ambient) = 16:0 K to Tc(P = 12:1 kbar) = 23:5 K was observed. In addition, a marked difference in the magnetic behavior is observed above and below 7.1 kbar. Specifically, for P < 7:1 kbar, the differences between the field-cooled and zero-field-cooled (fc-zfc) magnetizations, the coercive field, and the remanent magnetization decrease with increasing pressure. However, for P > 7:1 kbar, the behavior is inverted. Additionally, for P > 8:6 kbar, minor hysteresis loops are observed. All of these effects are evidence of the increase of the superexchange interaction and the appearance of an enhanced exchange anisotropy with applied pressure.

  8. Insight into the Atomic Structure of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material in the First Cycle

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huang, Xuejie; Yu, Xiqian; Lin, Mingxiang; Ben, Liubin; Sun, Yang; Wang, Hao; Yang, Zhenzhong; Gu, Lin; Yang, Xiao -Qing; Zhao, Haofei; et al

    2015-01-13T23:59:59.000Z

    Application of high-voltage spinel LiNi0.5Mn1.5O4 cathode material is the closest and the most realistic approach to meeting the midterm goal of lithium-ion batteries for electric vehicles (EVs) and plug-in hybrid electric vehicles (HEVs). However, this application has been hampered by long-standing issues, such as capacity degradation and poor first-cycle Coulombic efficiency of LiNi0.5Mn1.5O4 cathode material. Although it is well-known that the structure of LiNi0.5Mn1.5O4 into which Li ions are reversibly intercalated plays a critical role in the above issues, performance degradation related to structural changes, particularly in the first cycle, are not fully understood. Here, we report detailed investigations ofmore »local atomic-level and average structure of LiNi0.5Mn1.5O4 during first cycle (3.5–4.9 V) at room temperature. We observed two types of local atomic-level migration of transition metals (TM) ions in the cathode of a well-prepared LiNi0.5Mn1.5O4//Li half-cell during first charge via an aberration-corrected scanning transmission electron microscopy (STEM). Surface regions (~2 nm) of the cycled LiNi0.5Mn1.5O4 particles show migration of TM ions into tetrahedral Li sites to form a Mn3O4-like structure. However, subsurface regions of the cycled particles exhibit migration of TM ions into empty octahedral sites to form a rocksalt-like structure. The migration of these TM ions are closely related to dissolution of Ni/Mn ions and building-up of charge transfer impedance, which contribute significantly to the capacity degradation and the poor first-cycle Coulombic efficiency of spinel LiNi0.5Mn1.5O4 cathode material. Accordingly, we provide suggestions of effective stabilization of LiNi0.5Mn1.5O4 structure to obtain better electrochemical performance.« less

  9. Insight into the Atomic Structure of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material in the First Cycle

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Huang, Xuejie [Chinese Academy of Sciences, Beijing (China); Yu, Xiqian [Brookhaven National Laboratory (BNL), Upton, NY (United States); Lin, Mingxiang [Chinese Academy of Sciences, Beijing (China); Ben, Liubin [Chinese Academy of Sciences, Beijing (China); Sun, Yang [Chinese Academy of Sciences, Beijing (China); Wang, Hao [Chinese Academy of Sciences, Beijing (China); Yang, Zhenzhong [Chinese Academy of Sciences, Beijing (China); Gu, Lin [Chinese Academy of Sciences, Beijing (China); Yang, Xiao -Qing [Brookhaven National Laboratory (BNL), Upton, NY (United States); Zhao, Haofei [Chinese Academy of Sciences, Beijing (China); Yu, Richeng [Chinese Academy of Sciences, Beijing (China); Armand, Michel [CIC Energigune, Alava (Spain)

    2015-01-13T23:59:59.000Z

    Application of high-voltage spinel LiNi0.5Mn1.5O4 cathode material is the closest and the most realistic approach to meeting the midterm goal of lithium-ion batteries for electric vehicles (EVs) and plug-in hybrid electric vehicles (HEVs). However, this application has been hampered by long-standing issues, such as capacity degradation and poor first-cycle Coulombic efficiency of LiNi0.5Mn1.5O4 cathode material. Although it is well-known that the structure of LiNi0.5Mn1.5O4 into which Li ions are reversibly intercalated plays a critical role in the above issues, performance degradation related to structural changes, particularly in the first cycle, are not fully understood. Here, we report detailed investigations of local atomic-level and average structure of LiNi0.5Mn1.5O4 during first cycle (3.5–4.9 V) at room temperature. We observed two types of local atomic-level migration of transition metals (TM) ions in the cathode of a well-prepared LiNi0.5Mn1.5O4//Li half-cell during first charge via an aberration-corrected scanning transmission electron microscopy (STEM). Surface regions (~2 nm) of the cycled LiNi0.5Mn1.5O4 particles show migration of TM ions into tetrahedral Li sites to form a Mn3O4-like structure. However, subsurface regions of the cycled particles exhibit migration of TM ions into empty octahedral sites to form a rocksalt-like structure. The migration of these TM ions are closely related to dissolution of Ni/Mn ions and building-up of charge transfer impedance, which contribute significantly to the capacity degradation and the poor first-cycle Coulombic efficiency of spinel LiNi0.5Mn1.5O4 cathode material. Accordingly, we provide suggestions of effective stabilization of LiNi0.5Mn1.5O4 structure to obtain better electrochemical performance.

  10. Effect of oxygen concentration on the magnetic properties of La2CoMnO6 Center for Materials for Information Technology and Department of Chemistry, University of Alabama,

    E-Print Network [OSTI]

    Pennycook, Steve

    with the static FM Mn4+ ­O­Co2+ interactions. This results in the appearance of a new low temperature FM phase and suppression of the high-temperature FM phase, creating two distinct magnetic phase transitions. © 2007 Mn4+ ­O­Mn4+ or Co2+ ­O­Co2+ interactions in LCMO with the antisite ions.3 Even in an ordered double

  11. Structure and magnetic properties of low-temperature phase Mn-Bi nanosheets with ultra-high coercivity and significant anisotropy

    SciTech Connect (OSTI)

    Liu, Rongming, E-mail: rmliu@iphy.ac.cn, E-mail: shenbg@iphy.ac.cn; Zhang, Ming; Niu, E; Li, Zhubai; Zheng, Xinqi; Wu, Rongrong; Zuo, Wenliang; Shen, Baogen; Hu, Fengxia; Sun, Jirong [State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-05-07T23:59:59.000Z

    The microstructure, crystal structure, and magnetic properties of low-temperature phase (LTP) Mn-Bi nanosheets, prepared by surfactant assistant high-energy ball milling (SA-HEBM) with oleylamine and oleic acid as the surfactant, were examined with scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer, respectively. Effect of ball-milling time on the coercivity of LTP Mn-Bi nanosheets was systematically investigated. Results show that the high energy ball milling time from tens of minutes to several hours results in the coercivity increase of Mn-Bi powders and peak values of 14.3 kOe around 10 h. LTP Mn-Bi nanosheets are characterized by an average thickness of tens of nanometers, an average diameter of ?1.5??m, and possess a relatively large aspect ratio, an ultra-high room temperature coercivity of 22.3 kOe, a significant geometrical and magnetic anisotropy, and a strong (00l) crystal texture. Magnetization and demagnetization behaviors reveal that wall pinning is the dominant coercivity mechanism in these LTP Mn-Bi nanosheets. The ultrafine grain refinement introduced by the SA-HEBM process contribute to the ultra-high coercivity of LTP Mn-Bi nanosheets and a large number of defects put a powerful pinning effect on the magnetic domain movement, simultaneously. Further magnetic measurement at 437?K shows that a high coercivity of 17.8 kOe and a strong positive temperature coefficient of coercivity existed in the bonded permanent magnet made by LTP Mn-Bi nanosheets.

  12. Crystal structure of Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} (Ln=La, Pr and Nd): A new ordered rhombohedral pyrochlore

    SciTech Connect (OSTI)

    Fu, W.T., E-mail: w.fu@chem.leidenuniv.nl; IJdo, D.J.W.

    2014-05-01T23:59:59.000Z

    Manganese rare earth antimonates with the formula Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} (Ln=La–Yb and Y) have been prepared and their structures were determined by the Rietveld method using X-ray diffraction data. The compounds with Ln=La, Pr and Nd crystallize in a rhombohedral supercell of the cubic fluorite with the space group R3{sup ¯}m and with the lattice parameters a{sub h}??2a{sub c} and c{sub h}?2?3a{sub c}, where a{sub c} denotes the lattice constant of the cubic fluorite. The structure is pyrochlore-like but differs from the common cubic pyrochlore A{sub 2}B{sub 2}O{sub 7} in that it consists of fully ordered Mn:Ln in the A sites and Mn:Sb in the B sites with the ratio 1:3. The most interesting feature of Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} is that the divalent Mn ions have different coordination numbers with oxygen and the Mn(II)O{sub 6} (octahedron) and Mn(II)O{sub 8} (hexagonal bipyramid) alternate along the parent cubic fluorite axes. For medium sized lanthanides, i.e. from Ln=Sm, the rhombohedral phase coexists with the cubic phase and Mn{sub 2}Y{sub 3}Sb{sub 3}O{sub 14} is cubic a pyrochlore. - Graphical abstract: Crystal structure of rhombohedral pyrochlore Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} (Ln=La, Pr, and Nd) showing the staking of Ln{sub 3}Mn and MnSb{sub 3} layers (a). (b) and (c) show the connections between Mn1O{sub 6} and LnO{sub 8} and between Mn2O{sub 8} and SbO{sub 6} polyhedra, respectively. - Highlights: • Pyrochlores of the formula Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} (Ln=La–Yb and Y) were synthesized for the first time. • Mn{sub 2}Ln{sub 3}Sb{sub 3}O{sub 14} with Ln=La, Pr, Nd are rhombohedral consisting of fully 1:3 ordering of metal ions. • With medium-sized Ln, rhombohedral phase co-exists with cubic phase. • Two divalent Mn ions have coordination numbers of 6 and 8, respectively.

  13. Nanorods, nanospheres, nanocubes: Synthesis, characterization and catalytic activity of nanoferrites of Mn, Co, Ni, Part-89

    SciTech Connect (OSTI)

    Singh, Supriya; Srivastava, Pratibha [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India)] [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India); Singh, Gurdip, E-mail: gsingh4us@yahoo.com [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India)] [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India)

    2013-02-15T23:59:59.000Z

    Graphical abstract: Prepared nanoferrites were characterized by FE-SEM and bright field TEM micrographs. The catalytic effect of these nanoferrites was evaluated on the thermal decomposition of ammonium perchlorate using TG and TG–DSC techniques. The kinetics of thermal decomposition of AP was evaluated using isothermal TG data by model fitting as well as isoconversional method. Display Omitted Highlights: ? Synthesis of ferrite nanostructures (?20.0 nm) by wet-chemical method under different synthetic conditions. ? Characterization using XRD, FE-SEM, EDS, TEM, HRTEM and SAED pattern. ? Catalytic activity of ferrite nanostructures on AP thermal decomposition by thermal techniques. ? Burning rate measurements of CSPs with ferrite nanostructures. ? Kinetics of thermal decomposition of AP + nanoferrites. -- Abstract: In this paper, the nanoferrites of Mn, Co and Ni were synthesized by wet chemical method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive, X-ray spectra (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). It is catalytic activity were investigated on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG–DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + nanoferrites have also been investigated using isoconversional and model fitting approaches which have been applied to data for isothermal TG decomposition. The burning rate of CSPs was considerably enhanced by these nanoferrites. Addition of nanoferrites to AP led to shifting of the high temperature decomposition peak toward lower temperature. All these studies reveal that ferrite nanorods show the best catalytic activity superior to that of nanospheres and nanocubes.

  14. HAZ hardenability in welded C-Mn steels: The role of prior microstructure

    SciTech Connect (OSTI)

    Sarafinchin, D.; Patchett, B.M.

    1994-12-31T23:59:59.000Z

    The hardenability of the heat-affected zone (HAZ) in C-Mn steels is one of the primary influences on susceptibility to HAC in welded structures. Procedure control of HAZ hardness is based on the use of preheat and/or heat input to limit the peak HAZ hardness to 350--450 Hv10, depending on hydrogen level. Determination of procedural conditions depends on material thickness and carbon equivalent, but does not involve prior microstructure. This study investigated the influence of hot-rolled and normalized base metal microstructures on the level, development and location of peak hardness in steels of identical chemical composition. One heat of A516Gr70 steel in the hot-rolled condition was cut in two and one-half was normalized. This produced microstructures of differing grain size and pearlite coarseness. Gas tungsten arc welding (GTAW) fusion welds at two heat inputs (0.5 and 2.5 KJ/mm) were placed in each of the two base metals. Macro-and microhardness surveys and metallographic analysis were used o determine the location and level of HAZ hardness. Carbon gradients due to incomplete dissolution of cementite and lack of time for homogenization by diffusion cause significant differences in macro-and microhardness of HAZ constituents in A516Gr70 weld zones. Increased pearlite grain size, and to a lesser extent, pearlite lamellar thickness, produce martensitic zones of high hardness in hot-rolled A516Gr70 in two regions: at temperatures just over the A{sub 3} and at temperatures just over the A{sub 1}. Of the two, the region just over the A{sub 3} although removed from the fusion line, has the highest HAZ hardness and is most likely to be susceptible to HAC. Normalized steel is likely to be more resistant to HAC in the HAZ than hot-rolled steel of identical chemical composition.

  15. Effect of Mn doping on structural and magnetic susceptibility of C-type rare earth nano oxides Er{sub 2?x}Mn{sub x}O{sub 3}

    SciTech Connect (OSTI)

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt) [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)] [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2012-12-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? Er{sub 2?x}Mn{sub x}·O{sub 3} (0.0 ? x ? 0.20) prepared by sol–gel method. ? The change in lattice parameter is not linear with x due to the change in crystallite size with doping. ? Anomalous concentration dependence is found in magnetic susceptibility. ? The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x. ? Superexchange interactions between Er ions depending on the amount of Mn or Er in different sites. -- Abstract: The manganese doped rare earth oxides Er{sub 2?x}Mn{sub x} O{sub 3} (0.0 ? x ? 0.20) were synthesized by a sol–gel process and analyzed by X-ray diffraction using Rietveld refinement methods. A single phase solid solution is formed up to x = 0.15 while for x ? 0.2 a manganese oxide phase appears in the diffraction pattern. Preferential cationic distribution between the non-equivalent sites 8b and 24d of space group Ia3{sup ¯} is found for all samples but to a different extent. The octahedral volume and average bond length of Er{sub 1}-O for 8b site decrease while both octahedral volume and bond length of Er{sub 2}-O for 24d site increase. Magnetization measurements were done in the temperature range 5–300 K. The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x, except for sample x = 0.05 where the magnetization is enhanced. The Curie-Weiss paramagnetic temperatures indicate antiferromagnetic interaction.

  16. Preparation of magnetic photocatalyst nanoparticles—TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite—and its photocatalytic activity influenced by silica interlayer

    SciTech Connect (OSTI)

    Laohhasurayotin, Kritapas, E-mail: kritapas@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand); Pookboonmee, Sudarat; Viboonratanasri, Duangkamon; Kangwansupamonkon, Wiyong [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)

    2012-06-15T23:59:59.000Z

    Highlights: ? TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite acts as magnetic photocatalyst nanoparticle. ? SiO{sub 2} interlayer is used to prevent electron migration between photocatalyst and magnetic core. ? TiO{sub 2}/Mn–Zn ferrite without SiO{sub 2} interlayer shows poor magnetic and photocatalytic property. -- Abstract: A magnetic photocatalyst, TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite, was prepared by stepwise synthesis involving the co-precipitation of Mn–Zn ferrite as a magnetic core, followed by a coating of silica as the interlayer, and titania as the top layer. The particle size and distribution of magnetic nanoparticles were found to depend on the addition rate of reagent and dispersing rate of reaction. The X-ray diffractometer and transmission electron microscope were used to examine the crystal structures and the morphologies of the prepared composites. Vibrating sample magnetometer was also used to reveal their superparamagnetic property. The UV–Vis spectrophotometer was employed to monitor the decomposition of methylene blue in the photocatalytic efficient study. It was found that at least a minimum thickness of the silica interlayer around 20 nm was necessary for the inhibition of electron transference initiated by TiO{sub 2} and Mn–Zn ferrite.

  17. Structural phase transition and magnetism in hexagonal SrMnO{sub 3} by magnetization measurements and by electron, x-ray, and neutron diffraction studies

    SciTech Connect (OSTI)

    Daoud-Aladine, A.; Chapon, L. C.; Knight, K. S. [ISIS facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Martin, C. [Laboratoire CRISMAT-UMR, 6508 ENSI CAEN, 6, Marechal Juin, 14050 Caen (France); ISIS facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Hervieu, M. [Laboratoire CRISMAT-UMR, 6508 ENSI CAEN, 6, Marechal Juin, 14050 Caen (France); Brunelli, M. [European Synchrotron Radiation Facility, BP220, F-38043 Grenoble Cedex (France); Radaelli, P. G. [ISIS facility, Rutherford Appleton Laboratory-CCLRC, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2007-03-01T23:59:59.000Z

    The structural and magnetic properties of the hexagonal four-layer form of SrMnO{sub 3} have been investigated by combining magnetization measurements, electron diffraction, and high-resolution synchrotron x-ray and neutron powder diffraction. Below 350 K, there is subtle structural phase transition from hexagonal symmetry (space group P6{sub 3}/mmc) to orthorhombic symmetry (space group C222{sub 1}) where the hexagonal metric is preserved. The second-order phase transition involves a slight tilting of the corner-sharing Mn{sub 2}O{sub 9} units composed of two face-sharing MnO{sub 6} octahedra and the associated displacement of Sr{sup 2+} cations. The phase transition is described in terms of symmetry-adapted displacement modes of the high symmetry phase. Upon further cooling, long range magnetic order with propagation vector k=(0,0,0) sets in below 300 K. The antiferromagnetic structure, analyzed using representation theory, shows a considerably reduced magnetic moment indicating the crucial role played by direct exchange between Mn centers of the Mn{sub 2}O{sub 9} units.

  18. Neutron diffraction and electrochemical studies of Na0.79(Co,Mn)O2 cathodes for sodium-ion batteries

    SciTech Connect (OSTI)

    Beck, Faith R [National Energy Technology Laboratory (NETL); Cheng, Yongqiang [ORNL; Feygenson, Mikhail [ORNL; Bridges, Craig A [ORNL; Moorhead-Rosenberg, Z [Oak Ridge National Laboratory (ORNL); Manthiram, Arumugam [University of Texas at Austin; Goodenough, J. B. [University of Texas at Austin; Paranthaman, Mariappan Parans [ORNL; Manivannan, A. [National Energy Technology Laboratory (NETL)

    2014-01-01T23:59:59.000Z

    Na0.79CoO2 and Na0.79Co0.7Mn0.3O2 with a layered hexagonal structure (P2-type) were synthesized by the Pechini process followed by heat treatment at elevated temperatures in order to achieve the crystalline phases. The samples were characterized with x-ray diffraction, neutron diffraction, magnetic measurements and electrochemical charge-discharge cycling. X-ray diffraction confirmed the P2 layered hexagonal structure after heat treatment at 900 C in air. Neutron diffraction patterns confirm Mn doping on Co sites without forming pronounced Mn-Co ordering. Cyclic voltammetry showed the oxidation and reduction peaks of Co and Mn, indicating the intercalation and de-intercalation behavior of the Na ions. A discharge capacity of 60 mAh/g was achieved for both the compositions, with the Na0.79Co0.70Mn0.3O2 composition showing a more stable discharge capacity up to 60 cycles.

  19. Transmission electron microscopy (TEM) investigations of Mn-oxide rich cathodic material from spent disposable alkaline batteries

    SciTech Connect (OSTI)

    Krekeler, Mark P.S. [Department of Environmental Science and Policy, George Mason University, Fairfax, VA 22030 (United States)], E-mail: mark.krekeler@gmail.com

    2008-11-15T23:59:59.000Z

    Transmission electron microscopy (TEM) techniques were used to investigate the spent cathodic material of a single common brand of disposable alkaline batteries. Mn-oxide particles are anhedral and irregular in shape and compose an estimated 99-95% of the <10 {mu}m size fraction of sample material. Diameters of particles vary widely and typically are between 50 nm and 3 {mu}m; however, most particles are approximately 200-400 nm in diameter. Chemical composition varies for Mn-oxide particles with concentrations being SiO{sub 2} (0.00-1.52 wt%), TiO{sub 2} (0.49-4.58 wt%), MnO (65.85-92.06 wt%), ZnO (1.00-7.53 wt%), K{sub 2}O (4.97-20.48 wt%) and SO{sub 3} (0.43-2.21 wt%). Discrete prismatic zinc crystals occur and vary from a maximum of approximately 0.8 {mu}m long x 0.15 {mu}m wide, to 100 nm long x 20 nm wide. Titanium metal was also observed in samples and composes approximately 0.25-1.0% of the <10 {mu}m size fraction of sample material. Results of this study suggest that battery components may be recycled in some special applications. Examples are low energy-low material requirement products such as paint pigments and Zn nanoparticles. This investigation provides detailed constraints on the nature of spent cathodic materials to improve existing recycling methods and develop new technologies.

  20. Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

    SciTech Connect (OSTI)

    Maziasz, P.J.; Klueh, R.L.

    1988-01-01T23:59:59.000Z

    Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some sigma phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs.

  1. O3-type Na(Mn?.??Fe?.??Co?.??Ni?.??)O?: a quaternary layered cathode compound for rechargeable Na ion batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Xi [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Zhou, Yong-Ning [Brookhaven National Laboratory (BNL), Upton, NY (United States); Wu, Di [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Mechanical Engineering; Liu, Lei [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Ceder, Gerbrand [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Yang, Xiao-Qing [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2014-12-01T23:59:59.000Z

    We report a new layered Na(Mn?.??Fe?.??Co?.??Ni?.??)O? compound with O3 oxygen stacking. It delivers 180 mAh/g initial discharge capacity and 578 Wh/kg specific energy density with good cycling capability at high cutoff voltage. In situ X-ray diffraction (XRD) shows a reversible structure evolution of O3-P3-O3'-O3'' upon Na de-intercalation. The excellent capacity and cycling performance at high cutoff voltage make it an important model system for studying the general issue of capacity fading in layered Na cathode compounds.

  2. Energy Transfer Dynamics and Dopant Luminescence in Mn-Doped CdS/ZnS Core/Shell Nanocrystals

    E-Print Network [OSTI]

    Chen, Hsiang-Yun

    2012-11-13T23:59:59.000Z

    intensity calibration. A 370 nm light emitting diode was used as the excitation light source. . 32 Figure 9 Absorption spectra of Mn-doped CdS/ZnS nanocrystals with (sample 1, solid) and without (sample 2, dashed) Ostwald ripening with the same CdS core... with core size and shell thickness of 3.6 and ~1.8 nm, respectively. The luminescence spectra were taken using a CCD spectrometer (USB2000, Ocean Optics) without intensity calibration using a 370 nm light emitting diode as the excitation light source...

  3. (Cd,Mn)Te detectors for characterization of x-ray emissions generated during laser-driven fusion experiments

    SciTech Connect (OSTI)

    Cross,A.S.; Knauer, J. P.; Mycielski, A.; Kochanowska, D.; Wiktowska-Baran, M.; Jakiela, R.; Domagala, J.; Cui, Y.; James, R.; Sobolewski, R.

    2008-10-19T23:59:59.000Z

    We present our measurements of (Cd,Mn)Te photoconductive detectors (PCDs), fabricated for the goal of measuring both the temporal and spectral dependences of X-ray emissions generated from laser-illuminated targets during the inertial confinement fusion experiments. Our Cd{sub 1-x}Mn{sub x}Te (x = 0.05) single crystals, doped with V, were grown using a vertical Bridgman method and, subsequently, annealed in Cd for the highest resistivity ({approx}10{sup 10} {Omega}cm) and a good mobility-lifetime product ({approx}10{sup -3} cm{sup 2}/V). The 1-mm- and 2.3-mm-thick detectors were placed in the same housing as two 1-mm-thick diamond PCDs. All devices were pre-screened by a 7.6-mm-thick Be X-ray filter with a frequency cutoff of 1 keV. The incident shots from the OMEGA laser were 1-ns-long square pulses with energies ranging from 2.3 kJ to 22.6 kJ, and the PCDs were biased with 5000 V/cm. The response amplitudes and rise times of our (Cd,Mn)Te PCDs were comparable with the diamond detector performance, while the decay times were 4 to 10 times longer and in the 2-5 ns range. We observed two X-ray emission events separated by 1.24 ns. The first was identified as caused by heating of the target and creating a hot corona, while the second one was from the resulting compressed core. For comparison purposes, our testing was performed using {approx}1 keV X-ray photons, optimal for the diamond PCD. According to the presented simulations, however, at X-ray energies >10 keV diamond absorption efficiency drops to <50%, whereas for (Cd,Mn)Te the drop occurs at {approx}100 keV with near perfect, 100% absorption, up to 50 keV.

  4. Energy Transfer Dynamics and Dopant Luminescence in Mn-Doped CdS/ZnS Core/Shell Nanocrystals 

    E-Print Network [OSTI]

    Chen, Hsiang-Yun

    2012-11-13T23:59:59.000Z

    intensity calibration. A 370 nm light emitting diode was used as the excitation light source. . 32 Figure 9 Absorption spectra of Mn-doped CdS/ZnS nanocrystals with (sample 1, solid) and without (sample 2, dashed) Ostwald ripening with the same CdS core... with core size and shell thickness of 3.6 and ~1.8 nm, respectively. The luminescence spectra were taken using a CCD spectrometer (USB2000, Ocean Optics) without intensity calibration using a 370 nm light emitting diode as the excitation light source...

  5. Effect of Heat-Treatment on the Phases of Ni-Mn-Ga Magnetic Shape Memory Alloys

    SciTech Connect (OSTI)

    Huq, Ashfia [ORNL; Ari-Gur, Pnina [Western Michigan University; Kimmel, Giora [University of the Negev; Richardson, James W [Argonne National Laboratory (ANL); Sharma, Kapil [Indian Institute of Technology, Kanpur

    2009-01-01T23:59:59.000Z

    The Heusler alloys Ni50Mn25+xGa25-x display magnetic shape memory effect (MSM) with very fast and large reversible strain under magnetic fields. This large strain and the speed of reaction make MSM alloys attractive as smart materials. Our crystallographic investigation of these alloys, focused on non-stoichiometric composition with excess of manganese. Using neutron diffraction, we revealed the necessary processing parameters to achieve and preserve the homogeneous metastable one-phase martensitic structure that is needed for an MSM effect at room temperature.

  6. Effect of dopants on the magnetic properties of MnZn ferrites for high frequency power supplies

    SciTech Connect (OSTI)

    Znidarsic, A.; Limpel, M.; Drofenik, M. [Univ. of Ljubljana (Slovenia)] [Univ. of Ljubljana (Slovenia)

    1995-03-01T23:59:59.000Z

    The effect of additions on the magnetic properties of MnZn ferrites for high frequency power supplies was studied. The investigation revealed that various combinations of dopants added to the ferrite modify the grain boundary resistivity and the magnetic permeability spectra at constant microstructure. Particularly, the combined effect of Sn{sup 4+}, Ti{sup 4+} and Ta{sup 5+} was found to increase the grain boundary resistivity in the ferrites studied and remarkably decrease the power loss at higher frequencies.

  7. Electrochemical performance of polyaniline coated LiMn{sub 2}O{sub 4} cathode active material for lithium ion batteries

    SciTech Connect (OSTI)

    ?ahan, Halil, E-mail: halil@erciyes.edu.tr; Dokan, Fatma K?l?c, E-mail: halil@erciyes.edu.tr; Ayd?n, Abdülhamit, E-mail: halil@erciyes.edu.tr; Özdemir, Burcu, E-mail: halil@erciyes.edu.tr; Özdemir, Nazl?, E-mail: halil@erciyes.edu.tr; Patat, ?aban, E-mail: halil@erciyes.edu.tr [Department of Chemistry, Science Faculty, Erciyes University, Kayseri, 38039 (Turkey)

    2013-12-16T23:59:59.000Z

    LiMn{sub 2}O{sub 4} compound are synthesized by combustion method using glycine as a fuel at temperature (T), 800°C which was coated by a polyaniline. The goal of this procedure is to promote better electronic conductivity of the LiMn{sub 2}O{sub 4} particles in order to improve their electrochemical performance for their application as cathodes in secondary lithium ion batteries. The structures of prepared products have been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). To investigate the effect of polyaniline coating galvanostatic charge-discharge cycling (148 mA g{sup ?1}) studies are made in the voltage range of 3.5-4.5 V vs. Li at room temperature. Electrochemical performance of the LiMn{sub 2}O{sub 4} was significantly improved by the polaniline coating.

  8. Co doping enhanced giant magnetocaloric effect in Mn{sub 1-x}Co{sub x}As films epitaxied on GaAs (001)

    SciTech Connect (OSTI)

    Xu, P. F.; Nie, S. H.; Meng, K. K.; Wang, S. L.; Chen, L.; Zhao, J. H. [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2010-07-26T23:59:59.000Z

    A giant magnetocaloric effect was found in series of Mn{sub 1-x}Co{sub x}As films epitaxied on GaAs (001). The maximum magnetic entropy change caused by a magnetic field of 4 T is as large as 25 J/kg K around room temperature, which is about twice the value of pure MnAs film. The observed small thermal hysteresis is more suitable for practical application. Growing of layered Mn{sub 1-x}Co{sub x}As films with Co concentration changing gradually may draw layered active magnetic regenerator refrigerators closer to practical application. Our experimental result may provide the possibility for the combination of magnetocaloric effect and microelectronic circuitry.

  9. The crystal and magnetic structure of the magnetocaloric compound FeMnP{sub 0.5}Si{sub 0.5}

    SciTech Connect (OSTI)

    Hoeglin, Viktor, E-mail: viktor.hoglin@mkem.uu.se [Department of Materials Chemistry, Uppsala University, Box 538, 75121 Uppsala (Sweden); Hudl, Matthias [Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala (Sweden); Sahlberg, Martin [Department of Materials Chemistry, Uppsala University, Box 538, 75121 Uppsala (Sweden); Nordblad, Per [Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala (Sweden); Beran, Premysl [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Andersson, Yvonne [Department of Materials Chemistry, Uppsala University, Box 538, 75121 Uppsala (Sweden)

    2011-09-15T23:59:59.000Z

    The crystal and magnetic structure of the magnetocaloric compound FeMnP{sub 0.5}Si{sub 0.5} has been studied by means of neutron and X-ray powder diffraction. Single phase samples of nominal composition FeMnP{sub 0.5}Si{sub 0.5} have been prepared by the drop synthesis method. The compound crystallizes in the Fe{sub 2}P-type structure (P6-bar 2m) with the magnetic moments aligned along the a-axis. It is found that the Fe atoms are mainly situated in the tetrahedral 3g site while the Mn atoms prefer the pyramidal 3f position. The material is ferromagnetic (T{sub C}=382 K) and at 296 K the total magnetic moment is 4.4{mu}{sub B}/f.u. It is shown that the magnetic moment in the 3f site is larger (2.5{mu}{sub B}) than in the 3g site (1.9{mu}{sub B}). - Graphical abstract: The magnetic structure of FeMnP{sub 0.5}Si{sub 0.5} at 296 K. Revealed from refinements of neutron powder diffraction data. Highlights: > Single phase samples of the compound FeMnP{sub 0.5}Si{sub 0.5} has been synthesized by the drop synthesis method. > The crystal and magnetic structure was revealed from neutron powder diffraction data. > The material was found to crystallize in the Fe{sub 2}P-structure (P6-bar 2m). > The magnetic moments are coordinated along the a-axis with a total moment of 4.4{mu}{sub B}. > The large magnetic moments make FeMnP{sub 0.5}Si{sub 0.5} useful in magnetocaloric applications.

  10. Magnetocaloric effect of electron-doped manganite La{sub 0.9}Te{sub 0.1}MnO{sub 3}

    SciTech Connect (OSTI)

    Yang, J.; Lee, Y. P.; Li, Y. [Quantum Photonic Science Research Center, Hanyang University, Seoul 133-791, Korea and Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Materials Science and Engineering, Shijiazhuang University of Economics, Shijiazhuang, Hebei 050031 (China)

    2007-08-01T23:59:59.000Z

    The magnetocaloric effect of an electron-doped manganite La{sub 0.9}Te{sub 0.1}MnO{sub 3} has been investigated. The sample of La{sub 0.9}Te{sub 0.1}MnO{sub 3} undergoes the paramagnetic-ferromagnetic transition at 239 K. It is obtained that the effective magnetic moment ({mu}{sub eff}=4.923{mu}{sub B}) and the saturation moment ({mu}{sub S}=4.08{mu}{sub B}/Mn) are close to the respective expected values. The isothermal magnetization versus applied magnetic field at various temperatures between 180 and 300 K was measured, and the temperature dependence of magnetic entropy change |{delta}S{sub M}| for La{sub 0.9}Te{sub 0.1}MnO{sub 3} was understood. It is found that the sample shows a large magnetic entropy change near T{sub C} and the magnitude of magnetic entropy change is comparable to some hole-doped manganites. However, the relative cooling power of the electron-doped manganite La{sub 0.9}Te{sub 0.1}MnO{sub 3} is higher than that of some hole-doped manganites, which is an advantage for the engineer to design the magnetic refrigeration materials. Moreover, the temperature dependence of magnetic entropy change |{delta}S{sub M}| cannot be explained well based on the Landau theory of phase transition, and the contribution of the Jahn-Teller effect needs to be taken into account for La{sub 0.9}Te{sub 0.1}MnO{sub 3}.

  11. Transport and magnetism in La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3} and La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3} (abstract)

    SciTech Connect (OSTI)

    Rubinstein, M.; Tritt, T.M.; Synder, J.E. [U.S. Naval Research Laboratory, Washington, D.C. 20375 (United States)] [U.S. Naval Research Laboratory, Washington, D.C. 20375 (United States)

    1997-04-01T23:59:59.000Z

    La{sub 2/3}Ca{sub 1/3}MnO{sub 3} is a strong double-exchange ferromagnet where the ratio of La{sup 3+}{endash}Ca{sup 2+} ions has been chosen to maximize its favorable magnetic and transport properties. The Mn ion is unique as an effective participant in the double-exchange process. It is of interest to add Ni or Co atoms substitutionally for Mn in the form of La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3} and La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3} in order to determine the relative importance of the double-exchange interaction as the Mn concentration is reduced. Powder x-ray diffraction reveals we can retain the original orthorhombic structure of La{sub 2/3}Ca{sub 1/3}MnO{sub 3} (with up to 50{percent} Co or Ni substitution) by a series of anneals at 1300{degree}C followed by repeated grindings. We have investigated the magnetization, electrical conductivity, and thermopower of these mixed transition-metal perovskites. For La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3}, the magnetization decreases with added Co, but ferromagnetism is retained (at least up to 50{percent} Co). Although metallic conductivity is still present at 10{percent} Co concentration, these Co{endash}Mn perovskites become insulating for x{ge}0.2. For La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3}, the metallic state is retained at least until x=0.5. The magnetic properties exhibit spin-glasslike behavior for x{ge}0.25. {copyright} {ital 1997 American Institute of Physics.}

  12. Structures, electrical properties, and leakage current behaviors of un-doped and Mn-doped lead-free ferroelectric K{sub 0.5}Na{sub 0.5}NbO{sub 3} films

    SciTech Connect (OSTI)

    Wang, Lingyan, E-mail: l.y.wang@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn; Ren, Wei, E-mail: l.y.wang@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn; Shi, Peng; Wu, Xiaoqing [Electronic Material Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049 (China)

    2014-01-21T23:59:59.000Z

    Lead-free ferroelectric un-doped and doped K{sub 0.5}Na{sub 0.5}NbO{sub 3} (KNN) films with different amounts of manganese (Mn) were prepared by a chemical solution deposition method. The thicknesses of all films are about 1.6??m. Their phase, microstructure, leakage current behavior, and electrical properties were investigated. With increasing the amounts of Mn, the crystallinity became worse. Fortunately, the electrical properties were improved due to the decreased leakage current density after Mn-doping. The study on leakage behaviors shows that the dominant conduction mechanism at low electric field in the un-doped KNN film is ohmic mode and that at high electric field is space-charge-limited and Pool-Frenkel emission. After Mn doping, the dominant conduction mechanism at high electric field of KNN films changed single space-charge-limited. However, the introduction of higher amount of Mn into the KNN film would lead to a changed conduction mechanism from space-charge-limited to ohmic mode. Consequently, there exists an optimal amount of Mn doping of 2.0?mol.?%. The 2.0?mol.?% Mn doped KNN film shows the lowest leakage current density and the best electrical properties. With the secondary ion mass spectroscopies and x-ray photoelectron spectroscopy analyses, the homogeneous distribution in the KNN films and entrance of Mn element in the lattice of KNN perovskite structure were also confirmed.

  13. Temperature dependent electronic structure of Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film probed by X-ray absorption near edge structure

    SciTech Connect (OSTI)

    Zhang, Bangmin [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); NUSNNI-Nanocore, National University of Singapore, Singapore 117411 (Singapore); Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg; Heald, Steve M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, Jing-Sheng; Moog Chow, Gan, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Venkatesan, T. [NUSNNI-Nanocore, National University of Singapore, Singapore 117411 (Singapore); Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2014-05-07T23:59:59.000Z

    The Mn K edge X-ray absorption near edge structures (XANES) of Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film (100 nm) on (001) LaAlO{sub 3} substrate was measured at different temperatures to probe the MnO{sub 6} octahedron distortion and corresponding electronic structure. The absorption of high temperature paramagnetic-insulator phase differed from that of the low temperature ferromagnetic-metal phase. The temperature-dependent absorption intensity of Mn K edge XANES was correlated with the relaxation of distorted MnO{sub 6} octahedron, which changed the crystal field acting on the Mn site and the related electronic structure and properties. At low temperature, the splitting of Mn majority e{sub g} orbitals decreased and the density of states above the Fermi level increased in the relaxed MnO{sub 6} octahedron, as reflected by a wider separation between two sub-peaks in the pre-edge XANES spectra.

  14. Direct evidence on magnetic-field-induced phase transition in a NiCoMnIn ferromagnetic shape memory alloy under a stress field.

    SciTech Connect (OSTI)

    Wang, Y. D.; Ren, Y.; Huang, E. W.; Nie, Z. H.; Wang, G.; Liu, Y. D.; Deng, J. N.; Zuo, L.; Choo, H.; Liaw, P .K.; Brown, D. E.; Univ. of Tennessee; Northeastern Univ.; Northern Illinois Univ.

    2007-01-01T23:59:59.000Z

    The magnetoelasticity and magnetoplasticity behaviors of a Ni-Co-Mn-In ferromagnetic shape memory alloy (FSMA) induced by the reverse phase transformation interplayed under multiple (temperature, magnetic, and stress) fields were captured directly by high-energy synchrotron x-ray diffraction technique. The experiments showed the direct experimental evidence of that a stress ({approx}50 MPa) applied to this material made a complete recovery of the original orientations of the martensite variants, showing a full shape memory effect. This finding offers the in-depth understanding the fundamental properties and applications of the Ni-Co-Mn-In FSMA with the magnetic-field-induced reverse transformation.

  15. Synthesis and characterization of a novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite for supercapacitor

    SciTech Connect (OSTI)

    Li, Juan, E-mail: lj-panpan@163.com [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Que, Tingli [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China)] [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Huang, Jianbin, E-mail: JBhuang@pku.edu.cn [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2013-02-15T23:59:59.000Z

    Graphical abstract: A novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite have been successfully fabricated. Its inner tubules are CNTs and the outer tubules are template-synthesized PPy. Most MnO{sub 2} nanoparticles are sandwiched between the inner and outer wall, some relatively large particles are also latched onto the outside wall of the PPy tube. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test and galvanostatic charge–discharge experiments at different current densities. Display Omitted Highlights: ? We fabricate a ternary organic–inorganic complex of PPy/MnO{sub 2}/CNTs composite. ? We characterize its morphological structures and properties by several techniques. ? The composite possesses the typical tube-in-tube nanostructures. ? Most MnO{sub 2} nanoparticles are sandwiched between the inner CNTs and outer PPy wall. ? The composite has good electrochemical reversibility for supercapacitor. -- Abstract: Ternary organic–inorganic complex of polypyrrole/manganese dioxide/carbon nanotubes (PPy/MnO{sub 2}/CNTs) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO{sub 2} and CNTs, using complex of methyl orange (MO)/FeCl{sub 3} was used as a reactive self-degraded soft-template. The morphological structures of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopic (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively. All the results indicate that the PPy/MnO{sub 2}/CNTs composite possesses the typical tube-in-tube nanostructures: the inner tubules are CNTs and the outer tubules are template-synthesized PPy. MnO{sub 2} nanoparticles may either sandwich the space between the inner and outer tubules or directly latch onto the wall of the PPy tubes. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test in the potential range of ?0.6 to 0.4 V and its specific capacitance was up to 402.7 F g{sup ?1} at a current density of 1 A g{sup ?1} in galvanostatic charge–discharge experiment.

  16. Magnetic and magnetocaloric properties of Mn{sub 4–x}Fe{sub x}Ga?Sn

    SciTech Connect (OSTI)

    Eichenberger, L.; Malaman, B.; Mazet, T., E-mail: thomas.mazet@univ-lorraine.fr [Institut Jean Lamour, CNRS UMR 7198, Université de Lorraine, B.P. 70239, 54506 Vandoeuvre-lès-Nancy (France); Huang, J. H. [Baotou Research Institute of Rare Earths, Baotou 014030 (China)

    2014-09-14T23:59:59.000Z

    We investigate the magnetic and magnetocaloric properties of the new Mn{sub 4–x}Fe{sub x}Ga?Sn compounds (x = 0, 0.1, 0.4, 0.6, and 0.8) from DC magnetization measurements. These phases crystallize in a lacunar form of the ?-Fe{sub 2–x}Ge type of structure (P6?/mmc). They present a second-order paramagnetic to ferromagnetic transition whose temperature increases upon increasing the Fe content from TC=317 K for x=0 up to TC=411 K for x=0.8. The alloys with x?0.4 further exhibit another transition at lower temperature associated with a spin reorientation. The maximal magnetization and magnetic entropy change are found almost constant throughout the series close to ~7.4 ?B/f.u. and ~12 mJ cm³ K?¹ (for ???H=2.4 T), respectively. The magnetocaloric properties of Mn{sub 4–x}Fe{sub x}Ga?Sn are compared with those of previously investigated materials with high-temperature magnetic transition and their potential interest for high-temperature magnetocaloric applications is briefly discussed.

  17. Electrochromic properties of manganese oxide (MnO{sub x}) thin films made by electron beam deposition

    SciTech Connect (OSTI)

    Erlandsson, O.; Lindvall, J.; Nguyen Ngoc Toan; Nguyen Van Hung; Vu Thi Bich; Nguyen Nang Dinh [National Inst. of Physics of Vietnam, Hanoi (Viet Nam)

    1993-12-31T23:59:59.000Z

    In recent years, considerable attention has been given to both the theoretical and the experimental investigation of the physical and physico-chemical properties of the chromogenics materials due their favorable and promising applications such as electrochromic devices, energy-efficient smart windows, automobile mirrors and building glazings. Electrochromic MnO{sub x} thin films were prepared by using an electron beam technique followed by annealing post-treatment. Electrochromic properties of the films were studied in three different solutions: 1M LiClO{sub 4} in propylene carbonate, KOH (pH = 10.5) and natrium borate (pH = 9.2). The transmittance spectra of the colored films combined with their cyclic voltammograms have showed that the enhancement of the electrochromic behavior of these films can be attributed to the insertion (or extraction) of the OH{sup {minus}} anions into (or from) the MnO{sub x} films. The best electrochromic efficiency of the films was obtained in the borate electrolyte.

  18. Spin and orbital Ti magnetism at LaMnO3/SrTiO3 interfaces

    SciTech Connect (OSTI)

    Garcial-Barriocanal, J [Universidad Complutense, Spain; Cezar, J. C. [European Synchrotron Radiation Facility (ESRF); Bruno, F. Y. [Universidad Complutense, Spain; Thakur, P. [European Synchrotron Radiation Facility (ESRF); Brookes, N. B. [European Synchrotron Radiation Facility (ESRF); Utfeld, C. [University of Bristol, UK; Riviera-Calzada, A. [Universidad Complutense, Spain; Giblin, S. R. [ISIS Facility, Rutherford Appleton Laboratory; Taylor, J. W. [ISIS Facility, Rutherford Appleton Laboratory; Duffy, J. A. [University of Warwick, UK; Dugdale, S. B. [University of Bristol, UK; Nakamura, T. [Japan Synchrotron Radiation Research Institute, SPring-8; Kodama, K. [Japan Synchrotron Radiation Research Institute, SPring-8; Leon, C. [Universidad Complutense, Spain; Okamoto, Satoshi [ORNL; Santamaria, J. [Universidad Complutense, Spain

    2010-01-01T23:59:59.000Z

    In systems with strong electron-lattice coupling, such as manganites, orbital degeneracy is lifted, what causes a null expectation value of the orbital moment. Magnetic structure is thus determined by spin-spin superexchange. In titanates, however, with much smaller Jahn-Teller distortions, orbital degeneracy might allow non-zero values of the orbital magnetic moment. Accordingly, novel forms of ferromagnetic superexchange interaction unique to t2g electrons systems have been theoretically predicted, although their experimental observation has remained elusive. Here we report a new kind of Ti3+ ferromagnetism at LaMnO3/SrTiO3 epitaxial interfaces. It results from charge transfer to the empty conduction band of the titanate and has spin and orbital contributions evidencing the role played by orbital degeneracy. The possibility of tuning magnetic alignment (ferromagnetic or antiferromagnetic) of Ti and Mn moments by structural parameters is demonstrated. This result will provide important clues for the understanding of the effects of orbital degeneracy in superexchange coupling.

  19. Structural and magnetic heterogeneities, phase transitions, and magnetoresistance and magnetoresonance properties of the composition ceramic La{sub 0.7}Pb{sub 0.3-x}Sn{sub x}MnO{sub 3}

    SciTech Connect (OSTI)

    Pashchenko, V. P., E-mail: alpash@mail.ru; Pashchenko, A. V.; Prokopenko, V. K.; Revenko, Yu. F.; Burkhovetskii, V. V.; Shemyakov, A. A. [National Academy of Sciences of Ukraine, Galkin Institute for Physics and Engineering (Ukraine); Sil'cheva, A. G. [Luhansk Taras Shevchenko National University (Ukraine); Levchenko, G. G. [National Academy of Sciences of Ukraine, Galkin Institute for Physics and Engineering (Ukraine)

    2012-03-15T23:59:59.000Z

    The La{sub 0.7}Pb{sub 0.3-x}Sn{sub x}MnO{sub 3} composition ceramic is studied by X-ray diffraction, resistive, magnetic, electron-microscopic, magnetoresistance, and NMR ({sup 55}Mn, {sup 139}La) methods. The substitution of tin for lead results in structural phase separation into the basic perovskite (R3-bar c) and spinell (Fd3m), phases: La{sub 0.7}Pb{sub 0.3-x}Sn{sub x}MnO{sub 3} {yields} La{sub 0.7-x}Pb{sub 0.3-x}MnO{sub 3} + 0.5xLa{sub 2}Sn{sub 2}O{sub 7}. Changes in the lattice parameter of the basic perovskite R3-bar c structure, the electrical resistivity, and the magnetic and magnetoresistance properties are caused by changes in the composition and content of a conducting perovskite ferromagnetic phase, the Mn{sup 3+}/Mn{sup 4+} ratio, and the imperfection of vacancy and cluster types. An in-plane nanostructured cluster is formed by Mn{sup 2+} ions located in distorted A-positions. The detected anomalous magnetic hysteresis is induced by the appearance of a unidirectional exchange anisotropy at the boundary of an in-plane antifer-romagnetic cluster coherently joined with a ferromagnetic matrix structure. The broad asymmetric NMR spectra of {sup 55}Mn and {sup 139}La indicate a high-frequency Mn{sup 3+} {r_reversible} Mn{sup 4+} superexchange and a nonuniform distribution of ions and defects. The constructed phase diagram characterizes a strong relation between the magnetic and transport properties in rare-earth manganites.

  20. 1932 Inorganic Chemistry, Vol. 14, No. 8,1975 George M. Bodner Contribution from the William A. Noyes Laboratory,

    E-Print Network [OSTI]

    Bodner, George M.

    of tungsten carbonyl derivatives which question the generality of this correlation. A linear correlation may = C1, Me, OMe, OPh). The effect upon the carbonyl chemical shift of the replacement of X by Y replacement of carbonyl by phosphorus ligands. An excellent correlation is observed between the carbonyl

  1. Knowledge Zone: A Public Repository of Peer-Reviewed Biomedical Ontologies Kaustubh Supekar, Daniel Rubin, Natasha Noy, Mark Musen

    E-Print Network [OSTI]

    Rubin, Daniel L.

    that aims to facilitate ontology reuse has focused on building ontology libraries that are simple reposi these solutions, which is critical to the operation and long-term sustainability of the system. There have been some efforts to develop Web-based libraries of ontologies: Table 1 provides a listing of some

  2. IEEE Power and Energy Society General Meeting, July 2010, Minneapolis, MN USA c 2010 IEEE A cutset area concept for phasor monitoring

    E-Print Network [OSTI]

    Dobson, Ian

    IEEE Power and Energy Society General Meeting, July 2010, Minneapolis, MN USA c 2010 IEEE A cutset area concept for phasor monitoring Ian Dobson, Fellow IEEE ECE Department University of Wisconsin together voltage angle phasor measurements at several buses to measure the angle stress across an area

  3. Surface Modification of LiNi0.5Mn0.3Co0.2O2 Cathode for Improved Battery Performance 

    E-Print Network [OSTI]

    Lynch, Thomas

    2012-10-19T23:59:59.000Z

    This thesis details electrical and physical measurements of pulsed laser deposition-applied thin film coatings of Alumina, Ceria, and Yttria-stabilized Zirconia (YSZ) on a LiNi0.5Mn0.3Co0.2O2 (NMC) cathode in a Lithium ion battery. Typical NMC...

  4. EMSL Research and Capability Development Proposals Modeling-Assisted Growth of New Multiferroics in the MTiO3 (M = Fe, Mn, Ni) Family as

    E-Print Network [OSTI]

    in the MTiO3 (M = Fe, Mn, Ni) Family as Epitaxial Thin Films Project start date: July, 2011 EMSL Lead-quality epitaxial films of new multiferroic materials in the MTiO3 family by taking advantage of EMSL's oxide

  5. Contributions of the S100A9 C-Terminal Tail to High-Affinity Mn(II) Chelation by the Host-Defense Protein Human Calprotectin

    E-Print Network [OSTI]

    Nolan, Elizabeth M.

    Human calprotectin (CP) is an antimicrobial protein that coordinates Mn(II) with high affinity in a Ca(II)-dependent manner at an unusual histidine-rich site (site 2) formed at the S100A8/S100A9 dimer interface. We present ...

  6. A Large Manganese-doped Polyoxotitanate Nanocluster: Ti14MnO14(OH)2(OEt)28 Yang Chen,a

    E-Print Network [OSTI]

    Coppens, Philip

    containing titanium were stored and handled in a glove-box under a nitrogen atmosphere. Synthesis of Ti14Mn; Polyoxotitanate; Nanocluster; Crystal structure; Band gap. INTRODUCTION During the past decades, titanium dioxide as received: Titanium(IV) ethoxide (99+ %) was purchased from Alfa Aesar; manganese(III) acetate dihydrate (97

  7. Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Yuesheng [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Liu, Jue [Brookhaven National Lab. (BNL), Upton, NY (United States); Lee, Byungju [Seoul National Univ. (Korea, Republic of); Qiao, Ruimin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source; Yang, Zhenzhong [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Xu, Shuyin [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Yu, Xiqian [Brookhaven National Lab. (BNL), Upton, NY (United States)] (ORCID:000000018513518X); Gu, Lin [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Hu, Yong-Sheng [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP)] (ORCID:0000000284306474); Yang, Wanli [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source] (ORCID:0000000306668063); Kang, Kisuk [Seoul National Univ. (Korea, Republic of); Li, Hong [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP)] (ORCID:000000028659086X); Yang, Xiao-Qing [Brookhaven National Lab. (BNL), Upton, NY (United States); Chen, Liquan [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Huang, Xuejie [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP)

    2015-03-25T23:59:59.000Z

    The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, due to the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, e.g., Na0.44MnO2, were proposed, few negative electrode materials, e.g., activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accurately identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries.

  8. Unconventional Switching Behavior in La0.7Sr0.3MnO3/La0.7Sr0...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Unconventional Switching Behavior in La0.7Sr0.3MnO3La0.7Sr0.3CoO3 Exchange-spring Bilayer Monday, March 30, 2015 Interfacial magnetic interactions between ferromagnetic...

  9. Jet Simulation in a Diesel Engine James Glimm zx , M.N. Kim x , X.-L. Li z , R. Samulyak x , and Z.-L. Xu yz

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    Jet Simulation in a Diesel Engine James Glimm zx , M.N. Kim x , X.-L. Li z , R. Samulyak x , and Z and spray formation in a diesel engine by the Front Tracking method. We model mixed vapor-liquid region of a high speed diesel jet injected through a circular nozzle are the key to design a fuel e

  10. JOURNAL DE PHYSIQUE Colloque Cl, supplkment au no 4, Tome 38, Avril 1977, page Cl-341 HOT-ISOSTATIC PRESSING OF Mn-Zn FERRITES

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -ISOSTATIC PRESSING OF Mn-Zn FERRITES FOR MAGNETIC RECORDING HEADS C. BUTHKER and Th. BERBEN N. V. Philips Ceramic Laboratory-Building BE2 Eindhoven, Netherlands Resumb. -On produit des ferrites magnbtiques denses par sinteringand isostatichot pressing. The starting materials are normally sintered ferrites with closed porosity

  11. DOI: 10.1002/asia.200700054 Single-Crystalline and Near-Monodispersed NaMF3 (M=Mn, Co, Ni, Mg)

    E-Print Network [OSTI]

    Gao, Song

    importance.[1a,b,2] As important inorganic functional materials, complex metal fluorides such as AI MII F3, the NaMF3 (M=Mn, Co, Ni) nanoplates were partially aligned to form nanoar- rays on copper TEM grids Materials and Bioinorganic Chemistry Peking University, Beijing 100871 (China) Fax: (+86)10-6275-4179 E

  12. Reference: Dittrich, P., P. Speroni di Fenizio (2005), Chemical Organization Theory, arXiv:q-bio.MN/0501016 Chemical organization theory: Towards a theory of con-

    E-Print Network [OSTI]

    Dittrich, Peter

    2005-01-01T23:59:59.000Z

    Reference: Dittrich, P., P. Speroni di Fenizio (2005), Chemical Organization Theory, arXiv:q-bio.MN/0501016 Chemical organization theory: Towards a theory of con- structive dynamical systems Peter Dittrich. The theory consists of two parts. The first part introduces the concept of a chemical organization

  13. Graphene-oxide-coated LiNi0.5Mn1.5O4 as high voltage cathode for lithium ion batteries with high energy

    E-Print Network [OSTI]

    Zhou, Chongwu

    Graphene-oxide-coated LiNi0.5Mn1.5O4 as high voltage cathode for lithium ion batteries with high Since Sony rst commercialized lithium ion batteries in the early 1990s, the market for lithium ion of the great success of lithium ion battery technology developed for portable electronic devices, higher

  14. Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Yuesheng; Liu, Jue; Lee, Byungju; Qiao, Ruimin; Yang, Zhenzhong; Xu, Shuyin; Yu, Xiqian; Gu, Lin; Hu, Yong-Sheng; Yang, Wanli; et al

    2015-03-25T23:59:59.000Z

    The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, due to the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, e.g., Na0.44MnO2, were proposed, few negative electrode materials, e.g., activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accuratelymore »identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries.« less

  15. Terahertz dynamics of photogenerated carriers in ferromagnetic InGaMnAs G. A. Khodaparast, D. C. Larrabee, and J. Konoa)

    E-Print Network [OSTI]

    Natelson, Douglas

    response of InGaMnAs/InP by two-color pump­ probe spectroscopy, using an intense near-infrared beam used an intense picosecond pulse of near- infrared NIR radiation to create a large density of nonequilibrium carriers, which modifies the transmission and reflection of a delayed pulse of terahertz THz

  16. The effects of small metal additions ,,Co,Cu,Ga,Mn,Al,Bi,Sn... on the magnetocaloric properties of the Gd5Ge2Si2 alloy

    E-Print Network [OSTI]

    Kletetschka, Gunther

    .1 X=Fe,Cu,Co,Ga,Mn, or Al alloys are superior magnetic refrigerants compared to the undoped Gd5Ge2Si2 magnetic refrigerant because of its large "giant" magnetocaloric effect Sm between 270 and 300 K.1 more useful magnetic refrigerant than the undoped Gd5Ge2Si2 compound. Further, it was concluded

  17. Effect of partial substitution of Ni by Co on the magnetic and magnetocaloric properties of Ni50Mn35In15 Heusler alloy

    E-Print Network [OSTI]

    Adams, Philip W.

    /ferromagnetic transition (T ¼ TC). The effective refrigeration capacity at TM and TC for magnetizing field was found [magnetic entropy change (DSM), adiabatic temperature change (DTad), and refrigeration capacity (RC)] shouldEffect of partial substitution of Ni by Co on the magnetic and magnetocaloric properties of Ni50Mn

  18. Regrowth of diluted magnetic semiconductor GaMnAs on InGaP (001) surfaces to realize freestanding micromechanical structures

    SciTech Connect (OSTI)

    Choi, Hyung Kook; Lee, Joon Sue; Cho, Sung Woon; Lee, Won Oh; Shim, Seung Bo; Park, Yun Daniel [CSCMR and FPRD Department of Physics and Astronomy, Seoul National University, NS 50, Seoul 151- 747 (Korea, Republic of)

    2007-03-15T23:59:59.000Z

    Low temperature molecular beam epitaxy regrowths of Ga{sub 1-x}Mn{sub x}As (x{approx_equal}0.04) diluted magnetic semiconductors on GaAs/In{sub 1-y}Ga{sub y}P/GaAs(001) and In{sub 1-y}Ga{sub y}P/GaAs(001) (y{approx_equal}0.51) heterostructures prepared by metal-organic chemical vapor deposition are described. The resulting Ga{sub 1-x}Mn{sub x}As properties are comparable to epitaxial films grown directly on GaAs (001) substrates from in situ reflection high-energy electron diffraction, x-ray diffraction, magnetometry, and transport measurements with magnetic ordering temperature of as-grown films to range between {approx}50 and {approx}60 K. Postgrowth low temperature annealing enhances both magnetic and transport properties. Perfect etch selectivity between Ga{sub 1-x}Mn{sub x}As/GaAs and In{sub 1-y}Ga{sub y}P is utilized to realize suspended Ga{sub 1-x}Mn{sub x}As/GaAs doubly clamped beam micromechanical freestanding structures.

  19. Point defects as a test ground for the local density approximation +U theory: Mn, Fe, and V{sub Ga} in GaN

    SciTech Connect (OSTI)

    Volnianska, O.; Zakrzewski, T. [Institute of Physics PAS, 02-668 Warsaw (Poland); Boguslawski, P. [Institute of Physics PAS, 02-668 Warsaw (Poland); Institute of Physics, Kazimierz Wielki University, 85-072 Bydgoszcz (Poland)

    2014-09-21T23:59:59.000Z

    Electronic structure of the Mn and Fe ions and of the gallium vacancy V{sub Ga} in GaN was analysed within the GGA + U approach. First, the +U term was treated as a free parameter, and applied to p(N), d(Mn), and d(Fe). The band gap of GaN is reproduced for U(N) ? 4 eV. The electronic structure of defect states was found to be more sensitive to the value of U than that of the bulk states. Both the magnitude and the sign of the U-induced energy shifts of levels depend on occupancies, and thus on the defect charge state. The energy shifts also depend on the hybridization between defect and host states, and thus are different for different level symmetries. In the case of V{sub Ga}, these effects lead to stabilization of spin polarization and the “negative-U{sub eff}” behavior. The values of Us were also calculated using the linear response approach, which gives U(Fe) ? U(Mn) ? 4 eV. This reproduces well the results of previous hybrid functionals calculations. However, the best agreement with the experimental data is obtained for vanishing or even negative U(Fe) and U(Mn)

  20. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, Minneapolis, MN

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael

    2009-08-31T23:59:59.000Z

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology conducted in 2009 at the recently reconstructed I-35W bridge in Minneapolis, MN. The project was supported under the U.S. Department of Energy (DOE) Solid-State Lighting GATEWAY Technology Demonstration Program. Other participants in the demonstration project included the Minnesota Department of Transportation (Mn/DOT), Federal Highways Administration (FHWA), and BetaLED™ (a division of Ruud Lighting). Pacific Northwest National Laboratory (PNNL) conducted the measurements and analysis of the results. DOE has implemented a three-year evaluation of the LED luminaires in this installation in order to develop new longitudinal field data on LED performance in a challenging, real-world environment. This document provides information through the initial phase of the I-35W bridge project, up to and including the opening of the bridge to the public and the initial feedback received on the LED lighting installation from bridge users. Initial findings of the evaluation are favorable, with minimum energy savings level of 13% for the LED installation relative to the simulated base case using 250W high-pressure sodium (HPS) fixtures. The LEDs had an average illuminance level of 0.91 foot candles compared to 1.29 fc for the HPS lamps. The LED luminaires cost $38,000 more than HPS lamps, yielding a lengthy payback period, however the bridge contractor had offered to include the LED luminaires as part of the construction package at no additional cost. One potentially significant benefit of the LEDs in this installation is avoiding rolling lane closures on the heavily-traveled interstate bridge for the purpose of relamping the HPS fixtures. Rolling lane closures involve multiple crew members and various maintenance and safety vehicles, diversion of traffic, as well as related administrative tasks (e.g., approvals, scheduling, etc.). Mn/DOT records show an average cost of relamping fixtures along interstate roadways of between $130-150 per pole. The previous bridge saw a lamp mortality rate of approximately 50% every two years, though the new bridge was designed to minimize many of the vibration issues. A voluntary Web-based feedback survey of nearly 500 self-described bridge users showed strong preference for the LED lighting - positive comments outnumbered negative ones by about five-to-one.

  1. Improvements in electrical and dielectric properties of substituted multiferroic LaMnO{sub 3} based nanostructures synthesized by co-precipitation method

    SciTech Connect (OSTI)

    Mahmood, Azhar [Chemistry Department, Baghdad-ul-Jaded Campus, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)] [Chemistry Department, Baghdad-ul-Jaded Campus, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Warsi, Muhammad Farooq, E-mail: Farooq.warsi@iub.edu.pk [Chemistry Department, Baghdad-ul-Jaded Campus, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ashiq, Muhammad Naeem [Department of Chemistry, Bahauddin Zakaryia University of Multan-60000 (Pakistan)] [Department of Chemistry, Bahauddin Zakaryia University of Multan-60000 (Pakistan); Sher, Muhammad [Chemistry Department, The University of Sargodha, Sargodha 40100 (Pakistan)] [Chemistry Department, The University of Sargodha, Sargodha 40100 (Pakistan)

    2012-12-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? Simultaneous double ion substitutions philosophy is introduced in LaMnO{sub 3}. ? La{sub 1?x}Gd{sub x}Mn{sub 1?y}Cr{sub y}O{sub 3} nanoparticles are not reported previously. ? La{sub 1?x}Gd{sub x}Mn{sub 1?y}Cr{sub y}O{sub 3} nanoparticles are synthesized by co-precipitation method. ? The 12 fold increase in resistivity of LaMnO{sub 3} nanostructures is observed. -- Abstract: A series of La{sub 1?x}Gd{sub x}Mn{sub 1?y}Cr{sub y}O{sub 3} nanoparticles (where x, y = 0, 0.25, 0.50, 0.75 and 1.0) has been synthesized by the chemical co-precipitation method, involving double ion substitution philosophy. The nanoparticles were characterized by thermo gravimetric analysis (TGA), X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometer (VSM), DC electrical resistivity and dielectric measurements. The XRD and FTIR analysis confirmed the single orthorhombic phase and the crystallite size were found in the range of 16–34 nm. DC resistivity exhibited very interesting behavior which increased from 1.41 × 10{sup 8} to 16.35 ± 0.2 × 10{sup 8} ? cm upon complete double ions replacement of La and Mn with Gd and Cr, respectively. This very high resistivity variation upon substitution definitely would open new avenues for applications of these materials in microwave devices and other related areas. The dielectric properties of these nanoparticles were also studied at room temperature in the range of 6 kHz to 5 MHz and the maximum dielectric behavior (?? = 2.86 × 10{sup 3}, tan ? = 5.41, ?? = 15.5 × 10{sup 3}) was exhibited by La{sub 0.75}Gd{sub 0.25}Mn{sub 0.75}Cr{sub 0.25}O{sub 3} at 6 kHz. Hysteresis loops measurements showed that the synthesized nanomaterials are paramagnetic in nature at room temperature.

  2. Structural and magnetic characterization of BiFe{sub x}Mn{sub 2-x}O{sub 5} oxides (x=0.5, 1.0)

    SciTech Connect (OSTI)

    Retuerto, M., E-mail: retuerto@rci.rutgers.edu [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid (Spain); Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road Piscataway, NJ 08854-808 (United States); Martinez-Lope, M.J. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid (Spain); Krezhov, K. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Boulevard, Sofia 1784 (Bulgaria); Fernandez-Diaz, M.T. [Institut Laue-Langevin, BP156X, Grenoble F-38042 (France); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, E-28049 Madrid (Spain)

    2011-09-15T23:59:59.000Z

    The title compounds have been synthesized by a citrate technique followed by thermal treatments in air (BiFe{sub 0.5}Mn{sub 1.5}O{sub 5}) or under high oxygen pressure conditions (BiFeMnO{sub 5}), and characterized by X-ray diffraction (XRD), neutron powder diffraction (NPD) and magnetization measurements. The crystal structures have been refined from NPD data in the space group Pbam at 295 K. These phases are isostructural with RMn{sub 2}O{sub 5} oxides (R=rare earths) and contain infinite chains of Mn{sup 4+}O{sub 6} octahedra sharing edges, linked together by (Fe,Mn){sup 3+}O{sub 5} pyramids and BiO{sub 8} units. These units are strongly distorted with respect to those observed in other RFeMnO{sub 5} compounds, due to the presence of the electronic lone pair on Bi{sup 3+}. It is noteworthy the certain level of antisite disorder exhibited in both samples, where the octahedral positions are partially occupied by Fe cations, and vice versa. BiFe{sub x}Mn{sub 2-x}O{sub 5} (x=0.5, 1.0) are short-range magnetically ordered below 20 K for x=0.5 and at 40 K for x=1.0. The main magnetic interactions seem to be antiferromagnetic (AFM); however, the presence of a small hysteresis in the magnetization cycles indicates the presence of some weak ferromagnetic (FM) interactions. - Graphical Abstract: BiFe{sub x}Mn{sub 2-x}O{sub 5} (x=0.5, 1.0) samples are isostructural with BiMn{sub 2}O{sub 5}, belonging to the Pbam space group. The crystal structure contains infinite chains of edge-sharing Mn{sup 4+}O{sub 6} octahedra, interconnected by dimer units of Fe{sup 3+}O{sub 5} square pyramids. These units are strongly distorted due to the presence of the electronic lone pair on Bi{sup 3+}. They are magnetically ordered at low temperatures. The main magnetic interactions seem to be antiferromagnetic with the presence of some weak ferromagnetic response. Highlights: > Two new compounds of formula BiFe{sub x}Mn{sub 2-x}O{sub 5} (x=0.5, 1.0) have been obtained. > Their crystallographic structure is isotypical with that of RMn{sub 2}O{sub 5} materials. > The presence of the electronic lone pair on Bi{sup 3+} severely distorts the crystal structure. > There is no establishment of a long-range ferrimagnetic structure.

  3. Magnetic properties and magnetocaloric effect of NdMn{sub 2?x}Cu{sub x}Si{sub 2} compounds

    SciTech Connect (OSTI)

    Md Din, M. F., E-mail: mfmd999@uowmail.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Department of Electrical and Electronic Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Wang, J. L. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Avdeev, M.; Kennedy, S. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Gu, Q. F. [Australian Synchrotron, 800 Blackburn Rd, Clayton 3168 (Australia); Zeng, R.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia)

    2014-05-07T23:59:59.000Z

    Structural and magnetic properties of NdMn{sub 2?x}Cu{sub x}Si{sub 2} compounds (x?=?0–1.0) have been investigated by high intensity x-ray and resolution neutron diffraction (3–450?K), specific heat, dc magnetization, and differential scanning calorimetry measurements. Substitution of Cu for Mn leads to an increase in the lattice parameter a but a decrease in c at room temperature. Two magnetic phase transitions have been found for NdMn{sub 2?x}Cu{sub x}Si{sub 2} compounds with T{sub N} for the antiferromagnetic ordering of Mn-sublatttice and T{sub C} for the Nd-sublattice ferromagnetic ordering, respectively. T{sub C} increases significantly with increasing Cu content from 36?K at x?=?0 to 100?K at x?=?1.0. Moreover, it is found that the order of magnetic phase transition around T{sub C} also changes from first order at x?Mn. The values of ??S{sub M} around T{sub C} decrease with increasing x from 27?J kg{sup ?1} K{sup ?1} for x?=?0 to 0.5?J kg{sup ?1} K{sup ?1} for x?=?1.0 under 0–5?T field. Refinement of neutron diffraction patterns for x?=?0.2 confirms the magnetic states detected by magnetic study and also indicates that the lattice constants a and c show a distinct variation around T{sub C}.

  4. Magnetic field-induced phase transformation in NiMnCoIn magnetic shape memory alloys - a new actuation mechanism with large work output.

    SciTech Connect (OSTI)

    Karaca, H. E.; Karaman, I.; Basaran, B.; Ren, Y.; Chumlyakov, Y. I.; Maier, H. J.; X-Ray Science Division; Texsas A& M Univ.; Univ. of Kentucky; Siberian Physical-Technical Inst.; Univ. of Paderborn

    2009-04-09T23:59:59.000Z

    Magnetic shape memory alloys (MSMAs) have recently been developed into a new class of functional materials that are capable of magnetic-field-induced actuation, mechanical sensing, magnetic refrigeration, and energy harvesting. In the present work, the magnetic field-induced martensitic phase transformation (FIPT) in Ni{sub 45}Mn{sub 36.5}Co{sub 5}In{sub 13.5} MSMA single crystals is characterized as a new actuation mechanism with potential to result in ultra-high actuation work outputs. The effects of the applied magnetic field on the transformation temperatures, magnetization, and superelastic response are investigated. The magnetic work output of NiMnCoIn alloys is determined to be more than 1 MJ m{sup -3} per Tesla, which is one order of magnitude higher than that of the most well-known MSMAs, i.e., NiMnGa alloys. In addition, the work output of NiMnCoIn alloys is orientation independent, potentially surpassing the need for single crystals, and not limited by a saturation magnetic field, as opposed to NiMnGa MSMAs. Experimental and theoretical transformation strains and magnetostress levels are determined as a function of crystal orientation. It is found that [111]-oriented crystals can demonstrate a magnetostress level of 140 MPa T{sup -1} with 1.2% axial strain under compression. These field-induced stress and strain levels are significantly higher than those from existing piezoelectric and magnetostrictive actuators. A thermodynamical framework is introduced to comprehend the magnetic energy contributions during FIPT. The present work reveals that the magnetic FIPT mechanism is promising for magnetic actuation applications and provides new opportunities for applications requiring high actuation work-outputs with relatively large actuation frequencies. One potential issue is the requirement for relatively high critical magnetic fields and field intervals (1.5-3 T) for the onset of FIPT and for reversible FIPT, respectively.

  5. Estimated {sup 55}Mn and {sup 90}Zr Cross Section Covariances in the Fast Neutron Energy Region

    SciTech Connect (OSTI)

    Pigni, M.T. [National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)], E-mail: pigni@bnl.gov; Herman, M.; Oblozinsky, P. [National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2008-12-15T23:59:59.000Z

    We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from the keV energy range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by a perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.

  6. Neutron diffraction study of the magnetic-field-induced transition in Mn{sub 3}GaC

    SciTech Connect (OSTI)

    Çakir, Ö. [Physics Department, Yildiz Technical University, TR-34220 Esenler, Istanbul (Turkey); Physics Engineering Department, Ankara University, TR-06100 Ankara (Turkey); Acet, M.; Farle, M. [Faculty of Physics and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Senyshyn, A. [Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, D-85747 Garching bei München (Germany)

    2014-01-28T23:59:59.000Z

    The antiperovskite Mn{sub 3}GaC undergoes an isostructural cubic–cubic first order transition from a low-temperature, large-cell-volume antiferromagnetic state to a high-temperature, small-cell-volume ferromagnetic state at around 160?K. The transition can also be induced by applying a magnetic field. We study here the isothermal magnetic-field-evolution of the transition as ferromagnetism is stabilized at the expense of antiferromagnetism. We make use of the presence of the two distinct cell volumes of the two magnetic states as a probe to observe by neutron diffraction the evolution of the transition, as the external magnetic field carries the system from the antiferromagnetic to the ferromagnetic state. We show that the large-volume antiferromagnetic and the small-volume ferromagnetic states coexist in the temperature range of the transition. The ferromagnetic state is progressively stabilized as the field increases.

  7. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect (OSTI)

    Barabash, Rozaliya [ORNL; Xu, Ruqing [Argonne National Laboratory (ANL); Barabash, Oleg M [ORNL; Sozinov, Alexei [AdaptaMat, Finland

    2014-01-01T23:59:59.000Z

    Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

  8. Fabrication procedure for LiMn2O4/Graphite-based Lithium-ionRechargeable Pouch Cells

    SciTech Connect (OSTI)

    Liu, Gao; Zheng, Honghe; Battaglia, Vincent S.

    2007-04-30T23:59:59.000Z

    Procedures were developed at LBNL specifically for making electrodes and batteries of LiMn{sub 2}O{sub 4} (spinel) and MCMB (meso carbon micro beads) graphite for high-power applications (HEVs). Electrode performance can be very dependent on the materials used so it is pointed out that Toda M809 was used for the cathode active material and MCMB 10-28 from Osaka Gas was used for the anode active material. The conductive additives were Dankon black, an acetylene black, and SFG-6, a micron-size graphite. The binder used was PVdF (Kureha 1100). More details of these procedures can be found in the lab notebook of Gao Liu. These procedures are documented here but are continuously being refined, and should therefore be considered a work in progress.

  9. Structural and magnetic properties of Sm{sub 2?x}Mn{sub x}O{sub 3} nanoparticles

    SciTech Connect (OSTI)

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2013-10-15T23:59:59.000Z

    Graphical abstract: - Highlights: • C-type Sm{sub 2?x}Mn{sub x}O{sub 3} (0.0 ? x ?0.20) is prepared by sol–gel method. • A maximum solubility of x = 0.15 is confirmed by X-ray diffraction, Raman and infrared techniques. • Samples with x > 0.05 exhibit weak ferromagnetic properties; for x ? 0.05 antiferromagnetic behaviors is obtained. • Correlation between magnetic behaviors and structural and microstructural parameters is discussed. - Abstract: Mixed oxide Sm{sub 2?x}Mn{sub x}O{sub 3} (SMO), x = 0.0, 0.05, 0.10, 0.15 and 0.20 were synthesized by a sol–gel process. A single phase solid solution is formed up to x = 0.15 which confirmed by using X-ray diffraction, Raman spectroscopy and infrared techniques. Crystal structure and microstructure analyses were performed by Rietveld refinement. Preferential cationic distribution, over the two crystallographic sites 8b and 24d of space group Ia3{sup ¯}, is found for doped samples but with different extent. The r.m.s. microstrain ??{sub L}{sup 2}?{sup 1/2} depends on composition x in a systematic way emphasizing the preferential distribution. Magnetization measurements show that samples with x ? 0.05 have antiferromagnetic behavior, while samples with x > 0.05 exhibit a weak ferromagnetic behavior with magnetic phase transformation at 15 and 16 K for x = 0.1 and x = 0.15, respectively.

  10. Effect of boric acid on the properties of Li{sub 2}MnO{sub 3}·LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} composite cathode powders prepared by large-scale spray pyrolysis with droplet classifier

    SciTech Connect (OSTI)

    Hong, Young Jun; Choi, Seung Ho; Sim, Chul Min; Lee, Jung-Kul [Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701 (Korea, Republic of)] [Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Kang, Yun Chan, E-mail: yckang@konkuk.ac.kr [Department of Chemical Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701 (Korea, Republic of)

    2012-12-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? Spherical shape Li{sub 2}MnO{sub 3}·LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} composite cathode powders are prepared by large-scale spray pyrolysis with droplet classifier. ? Boric acid improves the morphological and electrochemical properties of the composite cathode powders. ? The discharge capacity of the composite cathode powders decreases from 217 to 196 mAh g{sup ?1} by the 30th cycle. -- Abstract: Spherically shaped 0.3Li{sub 2}MnO{sub 3}·0.7LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} composite cathode powders with filled morphology and narrow size distribution are prepared by large-scale spray pyrolysis. A droplet classification reduces the standard deviation of the size distribution of the composite cathode powders. Addition of boric acid improves the morphological properties of the product powders by forming a lithium borate glass material with low melting temperature. The optimum amount of boric acid dissolved in the spray solution is 0.8 wt% of the composite powders. The powders prepared from the spray solution with 0.8 wt% boric acid have a mixed layered crystal structure comprising Li{sub 2}MnO{sub 3} and LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} phases, thus forming a composite compound. The initial charge and discharge capacities of the composite cathode powders prepared from the 0.8 wt% boric acid spray solution are 297 and 217 mAh g{sup ?1}, respectively. The discharge capacity of the powders decreases from 217 to 196 mAh g{sup ?1} by the 30th cycle, in which the capacity retention is 90%.

  11. Substitution effect on the magnetic and transport properties of CeNi{sub 0.8?x}Mn{sub x}Bi{sub 2}

    SciTech Connect (OSTI)

    Kim, Soo-Whan; Lee, Kyujoon; Jung, Myung-Hwa, E-mail: mhjung@sognag.ac.kr [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Adroja, D. T. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa); Demmel, F.; Taylor, J. W. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2014-08-21T23:59:59.000Z

    We report the results of Mn substitution for Ni in CeNi{sub 0.8}Bi{sub 2} (i.e., CeNi{sub 0.8?x}Mn{sub x}Bi{sub 2}). All the samples have an antiferromagnetic ordered state below T{sub N}?=?5.0?K due to localized 4f-magnetic moment on the Ce ions. Besides this antiferromagnetic ordering caused by Ce, the magnetic and transport properties are abruptly changed with increasing Mn contents at the boundary composition of x?=?0.4. The magnetic state is changed into a ferromagnetic state around 200?K for x?>?0.4, where the electrical resistivity is strongly suppressed to become simple metallic. These results of ferromagnetism and metallicity can be explained by the double exchange mechanism, rather than the simple picture of Doniach phase diagram. The mixed valence states of Ni and Mn ions are confirmed by X-ray photoelectron spectroscopy. For x???0.4, the initial Ni{sup 3+} state gradually changes to the Ni{sup 2+} state with increasing x up to 0.4. On further increase of x?>?0.4, the Ni{sup 2+} state is replaced by the Mn{sup 2+} state, which gradually changes to the final Mn{sup 3+} state. We also present an inelastic neutron scattering (INS) measurements on CeNi{sub 0.8}Bi{sub 2} (i.e., x?=?0) between 1.2 and 12?K. The high energy INS study reveals the presence of two well-defined crystal electric field (CEF) excitations near 9?meV and 19?meV at 1.2?K and 6?K, while the low energy INS study reveals the presence of quasielastic scattering above 4?K. We will discuss our INS results of CeNi{sub 0.8}Bi{sub 2} based on the CEF model.

  12. Enhancement of exchange bias and training effect in ion-beam sputtered Fe{sub 46}Mn{sub 54}/Ni{sub 81}Fe{sub 19} bilayers

    SciTech Connect (OSTI)

    Fulara, Himanshu; Chaudhary, Sujeet, E-mail: sujeetc@physics.iitd.ac.in; Kashyap, Subhash C. [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Granville, Simon [Callaghan Innovation, PO Box 31310, Lower Hutt 5040 (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology, Lower Hutt (New Zealand)

    2014-01-28T23:59:59.000Z

    We present a remarkable enhancement by 300% of the exchange-bias field at room temperature, without affecting the coercivity value, via optimum magnetic annealing (250?°C/3 kOe) in ion-beam sputtered FeMn(30?nm)/NiFe(10?nm) bilayers. This specific behavior has been attributed to a higher degree of ?-FeMn(111) orientation that offers more interfacial FeMn moments to get pinned with the moments of the adjacent NiFe layer. Unlike the absence of training effect at room temperature, a pronounced training effect and an accompanying magnetization reversal asymmetry are evidenced upon field cooling below 50?K due to the presence of biaxial exchange induced anisotropy across the interdiffused FeMn/NiFe interface. The present findings not only have technological significance but also are of relevance to the understanding of interfacial spin disorder and frustration in these exchange-biased systems.

  13. Mon. Not. R. Astron. Soc. 000, 123 (2012) Printed 18 September 2012 (MN LATEX style file v2.2) Early-stage young stellar objects in the Small Magellanic Cloud

    E-Print Network [OSTI]

    Sloan, Gregory C.

    2012-01-01T23:59:59.000Z

    Mon. Not. R. Astron. Soc. 000, 1­23 (2012) Printed 18 September 2012 (MN LATEX style file v2 of Astronomy, University of Virginia, PO Box 3818, Charlottesville, VA 22903, USA 7 National Radio Astronomical

  14. Ab initio defect energetics of perovskite (001) surfaces for solid oxide fuel cells: A comparative study of LaMnO[subscript 3] versus SrTiO[subscript 3] and LaAlO[subscript 3

    E-Print Network [OSTI]

    Lee, Yueh-Lin

    In this paper, we perform a comparative study based on ab initio modeling for perovskite ABO[subscript 3] (001) surfaces and surface defect energetics in order to understand the influence of polarity and redox active Mn ...

  15. Magnetic ordering in TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} studied by neutron diffraction and first-principles calculations

    SciTech Connect (OSTI)

    Staruch, M. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Sharma, V.; Ramprasad, R. [Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Cruz, C. dela [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Jain, M. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-07-21T23:59:59.000Z

    The structure and magnetic ordering of bulk TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} was revealed through bulk magnetization and neutron diffraction measurements, and first-principles calculations, respectively. G-type antiferromagnetic ordering of Mn{sup 3+} and Cr{sup 3+} moments was observed in the neutron diffraction data below Néel temperature T{sub N}???84?K. In addition, below ?40?K, short-range magnetic ordering was identified correlating to a ferromagnetic component due to the canting of the moments along the c-axis. The spin configuration is consistent with the first-principles calculations. The magnetic structure revealed in the present TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} sample is distinct from that observed for both end members TbMnO{sub 3} and TbCrO{sub 3}.

  16. Layered Li1+x(Ni0.425Mn0.425Co0.15)1xO2 Positive Electrode Materials for Lithium-Ion Batteries

    E-Print Network [OSTI]

    Boyer, Edmond

    and Dahn to be due to an irreversible oxygen loss.14 Ever since LiNi1/3Mn1/3Co1/3O2 material was shown

  17. Synthesis and catalytic application of nanofibrous La{sub 0.9}A{sub 0.1}MnO{sub 3} (A = Ca, Cu, Ag) with macroscopic shapes

    SciTech Connect (OSTI)

    Wu, Qiang, E-mail: qiangwu@shiep.edu.cn; Zhao, Li; Wu, Jiang; Yao, Weifeng

    2013-10-15T23:59:59.000Z

    Graphical abstract: Fabrication of nanofibrous La{sub 0.9}A{sub 0.1}MnO{sub 3} (A = Ca, Cu, Ag) perovskite-type oxides with macroscopic shapes was successfully obtained using carbon nanofibers (CNFs) as templates. Furthermore, their application for the combustion of carbon black (CB), which is a model of particulate matter exhausted from diesel engines, was demonstrated. - Highlights: • Nanofibrous La{sub 0.9}A{sub 0.1}MnO{sub 3} with macroscopic shapes was successfully obtained. • CNFs template method used here is facile, effective and reproducible. • The obtained materials show superior catalytic activity in soot combustion. • The catalytic order is La{sub 0.9}Ag{sub 0.1}MnO{sub 3} > La{sub 0.9}Cu{sub 0.1}MnO{sub 3} > La{sub 0.9}Ca{sub 0.1}MnO{sub 3}. - Abstract: Fabrication of nanofibrous La{sub 0.9}A{sub 0.1}MnO{sub 3} (A = Ca, Cu, Ag) perovskite-type oxides with macroscopic shapes can be successfully obtained by using CNFs as templates. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis confirmed the template effect and formation of nanofibrous perovskite-type oxides on macroscopic silica fiber. It turned out that it is reliable to control the desired single-phase La{sub 0.9}A{sub 0.1}MnO{sub 3} (A = Ca, Cu, Ag) perovskite-type oxides formation by tuning the corresponding metal ratio during preparation process. Furthermore, it showed that the as-prepared nanofibrous La{sub 0.9}A{sub 0.1}MnO{sub 3} (A = Ca, Cu, Ag) perovskite-type oxides can greatly decrease the combustion temperature of nanosized carbon black particles, and follows the order of La{sub 0.9}Ag{sub 0.1}MnO{sub 3} > La{sub 0.9}Cu{sub 0.1}MnO{sub 3} > La{sub 0.9}Ca{sub 0.1}MnO{sub 3}, indicating their high potential application prospects in diesel soot particles treatment.

  18. Periodic Trends within a Series of Five-Coordinate Thiolate-Ligated [MII(SMe2N4(tren))]+ (M ) Mn, Fe, Co, Ni, Cu, Zn) Complexes, Including a

    E-Print Network [OSTI]

    Kovacs, Julie

    Periodic Trends within a Series of Five-Coordinate Thiolate-Ligated [MII(SMe2N4(tren))]+ (M ) Mn-ligated complexes [MII (tren)N4SMe2 ]+ (M ) Mn, Fe, Co, Ni, Cu, Zn; tren ) tris(2-aminoethyl)amine) are reported. All of the gem-dimethyl derivatized complexes are monomeric and, with the exception of [NiII (SMe2 N4

  19. Thermochromic effect at room temperature of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films

    SciTech Connect (OSTI)

    Boileau, A.; Capon, F.; Barrat, S.; Pierson, J. F. [Universite de Lorraine, Institut Jean Lamour, Departement CP2S, UMR CNRS 7198, Nancy, F-54042 (France); Laffez, P. [Groupe de Recherche Electronique, Materiaux, Acoustique, Nanoscience (GREMAN), Universite Francois Rabelais de Tours, UMR CNRS 7347, IUT de Blois, 15 rue de la Chocolaterie, Blois, F-41000 (France)

    2012-06-01T23:59:59.000Z

    Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thermochromic thin films were synthesized using dc reactive magnetron co-sputtering and subsequent annealing in air. The film structure was studied by x-ray diffraction analysis. To validate the thermochromic potentiality of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3}, electrical resistivity and infrared transmittance spectra were recorded for temperatures ranging from 77 K to 420 K. The temperature dependence of the optical band gap was estimated in the near infrared range. Upon heating, the optical transmission decreases in the infrared domain showing a thermochromic effect over a wide wavelength range at room temperature.

  20. Tuning exchange bias by Co doping in Mn??Ni{sub 41–x}Sn?Co{sub x} melt-spun ribbons

    SciTech Connect (OSTI)

    Zhao, D. W.; Li, G. K.; Wang, S. Q.; Ma, L., E-mail: majimei@126.com; Zhen, C. M.; Hou, D. L. [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024 (China); Wang, W. H.; Liu, E. K.; Chen, J. L.; Wu, G. H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-09-14T23:59:59.000Z

    In Mn??Ni{sub 41–x}Sn?Co{sub x} ribbons, the exchange bias field is very sensitive to the Co content. Based on both theoretical and experimental studies, it has been found that with increasing Co content, the pinned phase (ferromagnetic phase) remains almost unchanged while the pinning phase is changed from a canonical spin glass to a cluster spin glass and finally to a ferromagnetic phase. Changing the Co content in Mn??Ni{sub 41–x}Sn?Co{sub x} alloys has been proven to be an effective way of tuning the magnetic anisotropy and the phase structure of the pinning phase. With different Co contents, a continuous tuning of the exchange bias field from 345 Oe to 3154 Oe is realized.

  1. Evaluation of the intrinsic magneto-dielectric coupling in LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals

    SciTech Connect (OSTI)

    Manna, Kaustuv; Elizabeth, Suja; Anil Kumar, P. S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Joshi, Rajeev S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Department of Physics, Central University of Karnataka, Gulbarga 585106 (India)

    2014-05-19T23:59:59.000Z

    The magneto-dielectric coupling in (l00) oriented LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals has been investigated using temperature, frequency, and magnetic field dependent dielectric response. Electronic transport data divulges that polaronic hopping arises due to Emin-Holstein adiabatic small polarons. Spin realignment through external magnetic field favors faster polaronic hopping by lowering activation energy for dielectric relaxation. Finally, positive magneto-dielectricity and magnetoloss under increasing magnetic field at high frequency of the exciting ac field confirms intrinsic magneto-dielectric effect in disordered ferromagnetic-insulator LaMn{sub 0.5}Co{sub 0.5}O{sub 3}. This study also emphasizes the need to use single crystals as well as the frequencies higher than the corresponding inverse relaxation time.

  2. Magnetoresistance reversal in antiperovskite compound Mn{sub 3}Cu{sub 0.5}Zn{sub 0.5}N

    SciTech Connect (OSTI)

    Zhang, X. H.; Yin, Y.; Yuan, Q.; Han, J. C. [Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Zhang, Z. H. [Liaoning Key Materials Laboratory for Railway, School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028 (China); Jian, J. K. [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Zhao, J. G., E-mail: zhaojinggeng@163.com, E-mail: songbo@hit.edu.cn; Song, B., E-mail: zhaojinggeng@163.com, E-mail: songbo@hit.edu.cn [Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China)

    2014-03-28T23:59:59.000Z

    We report detailed investigations of the structure, magnetic properties, electronic transport, and specific heat in Mn-based antiperovskite compounds Mn{sub 3}Cu{sub 0.5}Zn{sub 0.5}N. Most strikingly, there are several fascinating features: (i) The magnetoresistance at 30?kOe (40?kOe) exceeds ?1% (?2%) over a temperature span of ?70?K (?25?K) from 5 to 140?K; (ii) magnetoresistance fluctuates at temperatures of 100–200?K, including an obvious sign reversal from negative to positive at ?140?K. Analysis of the specific heat reveals that the magnetoresistance reversal may originate from the reconstruction of the Fermi surface accompanying an antiferromagnetic-ferromagnetic transition.

  3. Magnetic properties of Ni40+xMn39-xSn21 (x=0, 2, 4, 6 and 8 at.%) Heusler alloys

    SciTech Connect (OSTI)

    Lazpita, P. [BCMaterials & UPV/EHU; Barandiaran, J. M. [BCMaterials & UPV/EHU; Chernenko, V. A. [BCMaterials & UPV/EHU; Garcia, B. Valle [UPV/EHU, EUITI Bilbao; Tajada, E. Diaz [Minera, Metalurgia y Ciencia de los Materiales, Spain; Lograsso, T. [Ames Laboratory; Schlagel, D. L. [Ames Laboratory

    2014-01-27T23:59:59.000Z

    The low electron concentration region (e/a < 7.75) of the magnetic phase diagram of the off-stoichiometric Ni–Mn–Sn Heusler alloys was investigated in detail by DSC and magnetization measurements of the Ni40+xMn39?xSn21(x = 0, 2, 4, 6 and 8 at.%) alloys. The alloys show a stable austenitic phase without any martensitic transformation down to 5 K even after heat treatment. The Curie temperature exhibits a broad maximum over a large composition range. The evolution of the magnetic moment with the electron concentration fits the data of previous studies and confirms the peak-like dependence in the extended range of e/a values predicted by ab initio calculations. The explored part of the moment versus e/a curve can be explained in terms of a localized magnetic moment model and full atomic order in the alloys.

  4. MICROSTRUCTURE STUDY ON THE La0.7Sr0.3MnO3 AND RARE-EARTH OXIDE VERTICALLY ALIGNED NANOCOMPOSITE THIN FILMS

    E-Print Network [OSTI]

    Hazariwala, Harshad

    2011-05-05T23:59:59.000Z

    interfacial area where magnetoelectric coupling in BaTiO3:CoFe2O4 and BiFeO3:NiFe2O4, 3,4 and strain tuning in BiFeO3:Sm2O3 and La0.7Sr0.3MnO3:ZnO have been achieved. 5 In this work, epitaxial La0.7Sr0.3MnO3 and rare-earth oxide nanocomposites have... interfaces. At the beginning of the project, we processed ceramic composite targets by following the standard solid state reaction and analyze the target crystalline properties in order to _______________ This thesis follows the style of Applied Physics...

  5. Participation of Glutamate-354 of the CP43 Polypeptide in the Ligation of Mn and the Binding of Substrate Water in Photosystem II

    SciTech Connect (OSTI)

    Service, Rachel; Yano, Junko; McConnell, Iain; Hwang, Hong Jin; Niks, Dimitri; Hille, Russ; Wydrzynski, Tom; Burnap, Robert; Hillier, Warwick; Debus, Richard

    2010-09-30T23:59:59.000Z

    In the current X-ray crystallographic structural models of photosystem II, Glu354 of the CP43 polypeptide is the only amino acid ligand of the oxygen-evolving Mn4Ca cluster that is not provided by the D1 polypeptide. To further explore the influence of this structurally unique residue on the properties of the Mn4Ca cluster, the CP43-E354Q mutant of the cyanobacterium Synechocystis sp. PCC 6803 was characterized with a variety of biophysical and spectroscopic methods, including polarography, EPR, X-ray Absorption, FTIR, and mass spectrometry. The kinetics of oxygen release in the mutant were essentially unchanged from those in wild-type. In addition, the oxygen flash-yields exhibited normal period-four oscillations having normal S state parameters, although the yields were lower, correlating with the mutant?s lower steady-state rate (approx. 20percent compared to wild-type). Experiments conducted with H218O showed that the fast and slow phases of substrate water exchange in CP43-E354Q thylakoid membranes were accelerated 8.5- and 1.8-fold, respectively, in the S3 state compared to wild-type. Purified oxygen-evolving CP43-E354Q PSII core complexes exhibited a slightly altered S1 state Mn-EXAFS spectrum, a slightly altered S2 state multiline EPR signal, a substantially altered S2-minus-S1 FTIR difference spectrum, and an unusually long lifetime for the S2 state (> 10 hours) in a substantial fraction of reaction centers. In contrast, the S2 state Mn-EXAFS spectrum was nearly indistinguishable from that of wild-type. The S2-minus-S1 FTIR difference spectrum showed alterations throughout the amide and carboxylate stretching regions. Global labeling with 15N and specific labeling with L-[1-13C]alanine revealed that the mutation perturbs both amide II and carboxylate stretching modes and shifts the symmetric carboxylate stretching modes of the ?-COO? group of D1-Ala344 (the C-terminus of the D1 polypeptide) to higher frequencies by 3 ? 4 cm-1 in both the S1 and S2 states. The EPR and FTIR data implied that 76 -82 percent of CP43-E354Q PSII centers can achieve the S2 state and that most of these can achieve the S3 state, but no evidence for advancement beyond the S3 state was observed in the FTIR data, at least not in a majority of PSII centers. Although the X-ray absorption and EPR data showed that the CP43-E354Q mutation only subtly perturbs the structure and spin state of the Mn4Ca cluster in the S2 state, the FTIR and H218O exchange data show that the mutation strongly influences other properties of the Mn4Ca cluster, altering the response of numerous carboxylate and amide groups to the increased positive charge that develops on the cluster during the S1 to S2 transition and weakening the binding of both substrate water molecules (or water derived ligands), especially the one that exchanges rapidly in the S3 state. The FTIR data provide evidence that CP43-Glu354 coordinates to the Mn4Ca cluster in the S1 state as a bridging ligand between two metal ions, but provide no compelling evidence that this residue changes its coordination mode during the S1 to S2 transition. The H218O exchange data provide evidence that CP43-Glu354 interacts with the Mn ion that ligates the substrate water molecule (or water-derived ligand) that is in rapid exchange in the S3 state.

  6. MN Center for Renewable Energy: Cellulosic Ethanol, Optimization of Bio-fuels in Internal Combustion Engines, & Course Development for Technicians in These Areas

    SciTech Connect (OSTI)

    John Frey

    2009-02-22T23:59:59.000Z

    This final report for Grant #DE-FG02-06ER64241, MN Center for Renewable Energy, will address the shared institutional work done by Minnesota State University, Mankato and Minnesota West Community and Technical College during the time period of July 1, 2006 to December 30, 2008. There was a no-cost extension request approved for the purpose of finalizing some of the work. The grant objectives broadly stated were to 1) develop educational curriculum to train technicians in wind and ethanol renewable energy, 2) determine the value of cattails as a biomass crop for production of cellulosic ethanol, and 3) research in Optimization of Bio-Fuels in Internal Combustion Engines. The funding for the MN Center for Renewable Energy was spent on specific projects related to the work of the Center.

  7. Strain-induced orbital polarization and multiple phase transitions in Ba{sub 2}MnWO{sub 6} from first principles

    SciTech Connect (OSTI)

    Ju, Weiwei; Zhao, Bao; Yang, Zhongqin, E-mail: zyang@fudan.edu.cn [State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433 (China)] [State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433 (China)

    2013-11-28T23:59:59.000Z

    Electronic structures of double perovskite Ba{sub 2}MnWO{sub 6} with epitaxial strain are explored by using methods based on density functional theory. An in-plane compressive strain is found not only resulting in a semiconductor-metal transition (SMT), but also altering the magnetic structures, from different kinds of antiferromagnetic to ferromagnetic orders. Orbital polarization and different orbital occupancies of Mn d{sub z{sup 2}} and d{sub x{sup 2}?y{sup 2}} states, induced by the epitaxial strain, are employed to understand the SMT. The rich magnetic phase transitions are rationalized by a magnetic stabilization mechanism. Our results show that many technological applications may be carried out in the material with the control of epitaxial strain.

  8. (Ca,Na)(Zn,Mn){sub 2}As{sub 2}: A new spin and charge doping decoupled diluted ferromagnetic semiconductor

    SciTech Connect (OSTI)

    Zhao, K.; Chen, B. J.; Deng, Z.; Zhao, G. Q.; Zhu, J. L.; Liu, Q. Q.; Wang, X. C. [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Collaborative Innovation Center of Quantum Matter, Beijing (China); Han, W. [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Collaborative Innovation Center of Quantum Matter, Beijing (China); Department of Physics, Chengde Mingzu College, Chengde (China); Frandsen, B.; Liu, L.; Cheung, S.; Uemura, Y. J. [Department of Physics, Columbia University, New York, New York 10027 (United States); Ning, F. L. [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Munsie, T. J. S.; Medina, T.; Luke, G. M. [Department of Physics and Astronomy, McMaster University, Hamilton, L8S 4M1 (Canada); Carlo, J. P. [Department of Physics, Villanova University, Villanova, Pennsylvania 19085 (United States); Munevar, J. [Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro (Brazil); Zhang, G. M. [Department of Physics, Tsinghua University, Beijing (China); Jin, C. Q., E-mail: JIN@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Collaborative Innovation Center of Quantum Matter, Beijing (China); Department of Physics, Columbia University, New York, New York 10027 (United States)

    2014-10-28T23:59:59.000Z

    Here, we report the successful synthesis of a spin- and charge-decoupled diluted magnetic semiconductor (DMS) (Ca,Na)(Zn,Mn){sub 2}As{sub 2}, crystallizing into the hexagonal CaAl{sub 2}Si{sub 2} structure. The compound shows a ferromagnetic transition with a Curie temperature up to 33?K with 10% Na doping, which gives rise to carrier density of n{sub p}???10{sup 20?}cm{sup ?3}. The new DMS is a soft magnetic material with H{sub C}?Mn doping, ferromagnetic order is accompanied by an interaction between the local spin and mobile charge, giving rise to a minimum in resistivity at low temperatures and localizing the conduction electrons. The system provides an ideal platform for studying the interaction of the local spins and conduction electrons.

  9. HYPERFINE-DEPENDENT gf-VALUES OF Mn I LINES IN THE 1.49-1.80 ?m H BAND

    SciTech Connect (OSTI)

    Andersson, M.; Hutton, R.; Zou, Y. [The Key Lab of Applied Ion Beam Physics, Ministry of Education (China); Grumer, J.; Brage, T. [Division of Mathematical Physics, Department of Physics, Lund University (Sweden); Ryde, N.; Blackwell-Whitehead, R. [Department of Astronomy and Theoretical Physics, Lund University (Sweden); Jönsson, P., E-mail: rhutton@fudan.edu.cn [School of Technology, Malmö University (Sweden)

    2015-01-01T23:59:59.000Z

    The three Mn I lines at 17325, 17339, and 17349 Å are among the 25 strongest lines (log (gf) > 0.5) in the H band. They are all heavily broadened due to hyperfine structure, and the profiles of these lines have so far not been understood. Earlier studies of these lines even suggested that they were blended. In this work, the profiles of these three infrared (IR) lines have been studied theoretically and compared to experimental spectra to assist in the complete understanding of the solar spectrum in the IR. It is shown that the structure of these lines cannot be described in the conventional way using the diagonal A and B hyperfine interaction constants. The off-diagonal hyperfine interaction not only has a large impact on the energies of the hyperfine levels, but also introduces a large intensity redistribution among the hyperfine lines, changing the line profiles dramatically. By performing large-scale calculations of the diagonal and off-diagonal hyperfine interaction and the gf-values between the upper and lower hyperfine levels and using a semi-empirical fitting procedure, we achieved agreement between our synthetic and experimental spectra. Furthermore, we compare our results with observations of stellar spectra. The spectra of the Sun and the K1.5 III red giant star Arcturus were modeled in the relevant region, 1.73-1.74 ?m, using our theoretically predicted gf-values and energies for each individual hyperfine line. Satisfactory fits were obtained and clear improvements were found using our new data compared with the old available Mn I data. A complete list of energies and gf-values for all the 3d {sup 5}4s({sup 7} S)4d e{sup 6}D - 3d {sup 5}4s({sup 7} S)4f w{sup 6}F hyperfine lines are available as supporting material, whereas only the stronger lines are presented and discussed in detail in this paper.

  10. {sup 238}U-{sup 234}U-{sup 230}Th chronometry of Fe-Mn crusts: Growth processes and recovery of thorium isotopic ratios of seawater

    SciTech Connect (OSTI)

    Chabaux, F.; Cohen, A.S.; O`Nions, R.K. [Univ. of Cambridge (United Kingdom)] [Univ. of Cambridge (United Kingdom); Hein, J.R. [Geological Survey, Menlo Park, CA (United States)] [Geological Survey, Menlo Park, CA (United States)

    1995-02-01T23:59:59.000Z

    Comparison of ({sup 234}U){sub excess}/({sup 238}U) and ({sup 230}Th)/({sup 232}Th) activity ratios in oceanic Fe-Mn deposits provides a method for assessing the closed-system behaviour of {sup 238}U-{sup 234}U-{sup 230}Th, as well as variations in the initial uranium and thorium isotopic ratios of the precipitated metal oxides. This approach is illustrated using a Fe-Mn crust from Lotab seamount (Marshall Islands, west equatorial Pacific). Here we report uranium and thorium isotopic compositions in five subsamples from the surface of one large 5 cm diameter botyroid of this crust, and from two depth profiles of the outermost rim of the same botyroid. The decrease of ({sup 234}U){sub excess}/({sup 238}U) and ({sup 230}Th/{sup 232}Th) activity ratio with depth in the two profiles gives mean growth rates, for the last 150 ka, of 7.8 {+-} 2 mm/Ma and 6.6 {+-} 1 mm/Ma, respectively. All data points (surface and core samples) but one, define a linear correlation in the Ln ({sup 230}Th/{sup 232}Th) - Ln [({sup 234}U){sub excess}({sup 238}U)] diagram. This correlation indicates that for all points the U-Th system remained closed after the Fe-Mn layer precipitated, and that the different samples possessed the same initial Uranium and thorium isotope ratios. Furthermore, these results show that the preserved surface of this Fe-Mn crust may not be the present-day growth surface, and that the thorium and uranium isotopic ratios of seawater in west equatorial Pacific have not changed during the past 150 ka. The initial thorium activity ratio is estimated from the correlation obtained between Ln({sup 230}Th/{sup 232}Th) and Ln [({sup 234}U){sub excess}/({sup 238}U)].

  11. Magneto-resistive coefficient enhancement observed around Verwey-like transition on spinel ferrites XFe{sub 2}O{sub 4} (X?=?Mn, Zn)

    SciTech Connect (OSTI)

    López Maldonado, K. L., E-mail: liliana.lopez.maldonado@gmail.com; Vazquez Zubiate, L.; Elizalde Galindo, J. T. [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310 Ciudad Juárez (Mexico); Presa, P. de la [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC), P.O. Box 155, 28230 Las Rozas (Spain); Departamento de Física de Materiales, Univ. Complutense de Madrid, Madrid (Spain); Matutes Aquino, J. A. [Centro de Investigación en Materiales Avanzados, Miguel de Cervantes 120, 31109 Chihuahua (Mexico)

    2014-05-07T23:59:59.000Z

    Manganese and Zinc ferrites were prepared by solid state reaction. The resulting powders were pressed into pellets and heat treated at 1100?°C. The samples were characterized by using X-ray diffraction, pure phases of zinc ferrite (ZnFe{sub 2}O{sub 4}) and manganese ferrite (MnFe{sub 2}O{sub 4}) were obtained. Scanning electron microscopy images showed a good contact between particles. A drop of electrical resistance was found in both samples, MnFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4}, with values going from 2750 to 130?? and from 1100 to 55??, respectively. Transition temperatures were determined to be T{sub V}?=?225?K for MnFe{sub 2}O{sub 4} and T{sub V}?=?130?K for ZnFe{sub 2}O{sub 4}. Magnetoresistance measurements were carried out in the temperature range where R showed the transition, defined as the Verwey-like transition temperature range, ?T{sub V}. No magnetoresistive effect was observed out of it. The magnetoresistive coefficient (MRC) observed at ?T{sub V} reached its maximum values of 1.1% for MnFe{sub 2}O{sub 4} and 6.68% for ZnFe{sub 2}O{sub 4}. The differences between MRC values are related to the divalent metal element used. Finally, the magnetoresistive response indicates that the electrical transition observed is strongly influencing the magnetoresistance; where the underlying responsible for this behavior could be a charge reordering occurring at the Verwey-like transition temperature.

  12. Towards the EDGE: Early diagenetic global explanation. A model depicting the early diagenesis of organic matter, O sub 2 , NO sub 3 , Mn, and PO sub 4

    SciTech Connect (OSTI)

    Rabouille, C.; Gaillard, J.F. (Univ. Paris 7 (France) Inst. de Physique du Globe de Paris (France))

    1991-09-01T23:59:59.000Z

    The ultimate fate of particles in aquatic environments is their burial and transformation in surficial sediments. There is an increasing need to relate quantitatively particle fluxes in the water column to the material recycled or preserved in the sediment. For this purpose, a transport-reaction model (EDGE) that represents the early diagenetic processes occurring in surficial sediments has been designed. This model uses the incoming flux of particulate matter and the overlying water composition in order to obtain simulated concentration profiles of chemical species in the bulk sediment and interstitial waters. It consists of a set of coupled nonlinear differential equations representing the oxidation of Particulate Organic Matter (POM) by a continuous sequence of electron acceptors (i.e., O{sub 2}, NO{sub 3}{sup {minus}}, MnO{sub 2}; in its preset state). The distribution of the concentrations of six components: POM, O{sub 2}, NO{sub 3}{sup {minus}}, MnO{sub 2}, Mn{sup 2+}, and {Sigma}PO{sub 4} are currently calculated. The Monod rate law has been used for representing the mineralization of POM coupled with the consumption of oxidants, and the sequence of oxidation of organic matter is represented using an inhibition function. The distributions with depth of the concentrations of the six chemical compounds are presented for different fluxes of POM at steady-state. These calculations show that the preservation of organic carbon and the extent of the mineralization processes are very sensitive to the organic carbon rain rate. For constant fluxes of POM and MnO{sub 2} arriving at the sediment water interface, the effect of an increasing sedimentation rate, as it might be produced by an augmentation of the detrital flux, is assessed on carbon preservation.

  13. Synthesis, crystal structure and properties of [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} with mixed-valent Ge centers

    SciTech Connect (OSTI)

    Yue, Cheng-Yang; Yuan, Zhuang-Dong; Zhang, Lu-Ge; Wang, Ya-Bai; Liu, Guo-Dong; Gong, Liao-Kuo [Key Laboratory of Inorganic Chemistry in Universities of Shandong, Department of Chemistry and Chemical Engineering, Jining University, Qufu, Shandong 273155 (China); Lei, Xiao-Wu, E-mail: xwlei_jnu@163.com [Key Laboratory of Inorganic Chemistry in Universities of Shandong, Department of Chemistry and Chemical Engineering, Jining University, Qufu, Shandong 273155 (China); State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100 (China)

    2013-10-15T23:59:59.000Z

    One new manganese thiogermanate, [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} (dien=diethylenetriamine), was prepared under mild solvothermal conditions and structurally and spectroscopically characterized. The title compound crystallizes in the orthorhombic system, chiral space group P2{sub 1}2{sub 1}2{sub 1} (no. 19) with a=9.113(4) Å, b=12.475(5) Å, c=17.077(7) Å, V=1941.5(15) Å{sup 3} and Z=4. Its structure features a three-dimensional (3D) network composed of a one-dimensional (1D) [Ge{sub 2}S{sub 4}]{sup 2?} anionic chain and a [(dien){sub 2}Mn]{sup 2+} complex interconnected via various hydrogen bonds. The most interesting structural feature of the compound is the presence of two different oxidation states of germanium centers in the 1D [Ge{sub 2}S{sub 4}]{sup 2?} chain, which is also supported by the result of X-ray photoelectron spectroscopy measurement. The optical property of the title compound has also been studied by UV–vis spectra. - Graphical abstract: One new thiogermanate, [(dien){sub 2}Mn]Ge{sub 2}S{sub 4}, contains a one-dimensional [Ge{sub 2}S{sub 4}]{sup 2?} anionic chain with two different oxidation states of germanium centers. Display Omitted - Highlights: • One new manganese thiogermanate [(dien){sub 2}Mn]Ge{sub 2}S{sub 4} was prepared. • The compound features 1D [Ge{sub 2}S{sub 4}]{sup 2?} chain composed of [Ge{sup II}S{sub 4}] and [Ge{sup IV}S{sub 4}] tetrahedra. • The first example of inorganic–organic hybrid thiogermanates with mixed valent Ge centers.

  14. X-ray micro-tomography investigation of the foaming process in the system of waste glass–silica mud–MnO{sub 2}

    SciTech Connect (OSTI)

    Ducman, V., E-mail: vilma.ducman@zag.si [ZAG Ljubljana, Dimi?eva 12, 1000 Ljubljana (Slovenia); Korat, L.; Legat, A. [ZAG Ljubljana, Dimi?eva 12, 1000 Ljubljana (Slovenia); Mirti?, B. [NTF, Ašker?eva 12, 1000 Ljubljana (Slovenia)

    2013-12-15T23:59:59.000Z

    In case of foamed lightweight aggregates (LWAs), porosity is introduced by the addition of a foaming agent to the glassy matrix, which degasses at an elevated temperature, so that the resulting gases remain trapped inside the glassy structure. The efficiency of action of MnO{sub 2} as a foaming agent in waste glass and waste glass/silica mud systems was studied. Samples were fired at different temperatures and with different dwelling times at a certain temperature, and the development of porosity was investigated by means of X-ray micro-tomography. It was found that, with the prolongation in dwelling times, the number of pores decreased, while, on the other hand, the volume of these pores increased, and that the addition of silica mud increases the foaming temperature and slows down the foaming process. - Highlights: • Preparation of lightweight aggregate from waste glass, silica sludge, and MnO{sub 2} • DTA/TG investigation of MnO{sub 2} • Characterization of pore-forming process by means of X-ray micro-tomography (?cT)

  15. A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe-Mn-C system exhibiting multicomposition sets

    SciTech Connect (OSTI)

    Nakano, Jinichiro

    2013-02-01T23:59:59.000Z

    Thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. Stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T{sub 0}, independent of composition and temperature when the other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced) hcp formation were separated by the SFE at T{sub 0}. The driving force for the fcc to hcp transition, defined as a dimensionless value –dG{sub m}/(RT), was determined in the presence of Fe-rich and Mn-rich composition sets in each phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the studied compositions. The obtained results revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.

  16. Martensitic transformation and phase stability of In-doped Ni-Mn-Sn shape memory alloys from first-principles calculations

    SciTech Connect (OSTI)

    Xiao, H. B. [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan 430062 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Yang, C. P., E-mail: cpyang@hubu.edu.cn; Wang, R. L.; Luo, X. [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan 430062 (China); Marchenkov, V. V. [Institute of Metal Physics, 620990 Ekaterinburg (Russian Federation)

    2014-05-28T23:59:59.000Z

    The effect of the alloying element Indium (In) on the martensitic transition, magnetic properties, and phase stabilities of Ni{sub 8}Mn{sub 6}Sn{sub 2?x}In{sub x} shape memory alloys has been investigated using the first-principles pseudopotential plane-wave method based on density functional theory. The energy difference between the austenitic and martensitic phases was found to increase with increasing In content, which implies an enhancement of the martensitic phase transition temperature (T{sub M}). Moreover, the formation energy results indicate that In-doping increases the relative stability of Ni{sub 8}Mn{sub 6}Sn{sub 2?x}In{sub x} both in austenite and martensite. This results from a reduction in density of states near the Fermi level regions caused by Ni-3d–In-5p hybridization when Sn is replaced by In. The equilibrium equation of state results show that the alloys Ni{sub 8}Mn{sub 6}Sn{sub 2?x}In{sub x} exhibit an energetically degenerated effect for an In content of x?=??1.5. This implies the coexistence of antiparallel and parallel configurations in the austenite.

  17. Changes of the local distortions and colossal magnetoresistive properties of La(0.7)Ca(0.3)MnO(3) induced by Ti or Ga defects

    SciTech Connect (OSTI)

    Bridges, F.; Cao, D.; Anderson, M.; Ramirez, A.P.; Olapinski, M.; Subramanian, M.A.; Booth, C.H.; Kwei, G.

    2002-07-12T23:59:59.000Z

    The magnetoresistive properties of La0.7Ca0.3MnO3 change rapidly when Ti or Ga are substituted on the Mn site for concentrations, x, from 1 to 10 percent. The samples exhibit colossal magnetoresistance (CMR) and the resistivity increases dramatically with dopant concentration. The temperature of the resistivity peak, TR, shifts rapidly to lower temperatures with increasing x and the ferromagnetic transition broadens. However, the transition temperature, Tc, is only slightly suppressed. Consequently, TR occurs well below Tc for x above 2 percent. Investigations of these materials using Mn XAFS show that changes in the local structure, parametrized by the pair-distribution width, sigma, correlate well with Tc and the sample magnetization. For a given dopant, the resistivity peak occurs when sigma{sup 2} decreases below a critical value. Both dopants produce extended defects which increases the resistivity of the nearby materials considerably. The data suggest that even at x {approx}4 percent, most of the sites are slightly distorted at low T.

  18. Effect of Zn doping on the magneto-caloric effect and critical constants of Mott insulator MnV{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Shahi, Prashant; Kumar, A.; Shukla, K. K.; Chatterjee, Sandip, E-mail: schatterji.app@iitbhu.ac.in [Department of Applied Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India); Singh, Harishchandra [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore - 452013 (India); Ghosh, A. K. [Department of Physics, Banaras Hindu University, Varanasi-221005 (India); Yadav, A. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai – 400 094 (India); Nigam, A. K. [Department of CMP and MS, Tata Institute of Fundamental Research, Mumbai-400005 (India)

    2014-09-15T23:59:59.000Z

    X-ray absorption near edge spectra (XANES) and magnetization of Zn doped MnV{sub 2}O{sub 4} have been measured and from the magnetic measurement the critical exponents and magnetocaloric effect have been estimated. The XANES study indicates that Zn doping does not change the valence states in Mn and V. It has been shown that the obtained values of critical exponents ?, ? and ? do not belong to universal class and the values are in between the 3D Heisenberg model and the mean field interaction model. The magnetization data follow the scaling equation and collapse into two branches indicating that the calculated critical exponents and critical temperature are unambiguous and intrinsic to the system. All the samples show large magneto-caloric effect. The second peak in magneto-caloric curve of Mn{sub 0.95}Zn{sub 0.05}V{sub 2}O{sub 4} is due to the strong coupling between orbital and spin degrees of freedom. But 10% Zn doping reduces the residual spins on the V-V pairs resulting the decrease of coupling between orbital and spin degrees of freedom.

  19. Functioning mechanism of AlF3 coating on the Li- and Mn-rich cathode materials

    SciTech Connect (OSTI)

    Zheng, Jianming; Gu, Meng; Xiao, Jie; Polzin, Bryant; Yan, Pengfei; Chen, Xilin; Wang, Chong M.; Zhang, Jiguang

    2014-11-25T23:59:59.000Z

    Li- and Mn-rich (LMR) material is a very promising cathode for lithium ion batteries because of their high theoretical energy density (~900 Wh kg-1) and low cost. However, their poor long-term cycling stability, voltage fade, and low rate capability are significant barriers hindered their practical applications. Surface coating, e.g. AlF3 coating, can significantly improve the capacity retention and enhance the rate capability. However, the fundamental mechanism of this improvement and the microstructural evolution related to the surface coating is still not well understood. Here, we report systematic studies of the microstructural changes of uncoated and AlF3-coated materials before and after cycling using aberration-corrected scanning/transmission electron microscopy and electron energy loss spectroscopy. The results reveal that surface coating can reduce the oxidation of electrolyte at high voltage, thus suppressing the accumulation of SEI layer on electrode particle surface. Surface coating also enhances structural stability of the surface region (especially the electrochemically transformed spinel-like phase), and protects the electrode from severe etching/corrosion by the acidic species in the electrolyte, therefore limiting the degradation of the material. Moreover, surface coating can alleviate the undesirable voltage fade by minimize layered-spinel phase transformation in the bulk region of the materials. These fundamental findings may also be widely applied to explain the functioning mechanism of other surface coatings used in a broad range of electrode materials.

  20. High temperature dielectric relaxation anomaly of Y{sup 3+} and Mn{sup 2+} doped barium strontium titanate ceramics

    SciTech Connect (OSTI)

    Yan, Shiguang; Mao, Chaoliang, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2014-10-14T23:59:59.000Z

    Relaxation like dielectric anomaly is observed in Y{sup 3+} and Mn{sup 2+} doped barium strontium titanate ceramics when the temperature is over 450?K. Apart from the conventional dielectric relaxation analysis method with Debye or modified Debye equations, which is hard to give exact temperature dependence of the relaxation process, dielectric response in the form of complex impedance, assisted with Cole-Cole impedance model corrected equivalent circuits, is adopted to solve this problem and chase the polarization mechanism in this paper. Through this method, an excellent description to temperature dependence of the dielectric relaxation anomaly and its dominated factors are achieved. Further analysis reveals that the exponential decay of the Cole distribution parameter n with temperature is confirmed to be induced by the microscopic lattice distortion due to ions doping and the interaction between the defects. At last, a clear sight to polarization mechanism containing both the intrinsic dipolar polarization and extrinsic distributed oxygen vacancies hopping response under different temperature is obtained.

  1. Noncollinear ferromagnetic easy axes in Py/Ru/FeCo/IrMn spin valves induced by oblique deposition

    SciTech Connect (OSTI)

    Bueno, T. E. P.; Parreiras, D. E.; Gomes, G. F. M.; Krambrock, K.; Paniago, R. [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG (Brazil); Michea, S.; Rodríguez-Suárez, R. L. [Centro de Investigación en Nanotecnología y Materiales Avanzados “CIEN-UC,” Pontifícia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Filho, M. S. Araújo; Macedo, W. A. A. [Laboratório de Física Aplicada, Centro de Desenvolvimento da Tecnologia Nuclear, 30123-970 Belo Horizonte, MG (Brazil)

    2014-06-16T23:59:59.000Z

    We present an investigation on the magnetic properties of Py/Ru/FeCo/IrMn spin valves grown by dc magnetron sputtering. The sample fabrication setup has two important features, (i) the five magnetron sputtering sources are placed in a cluster flange 72° from each other, and (ii) each source is tilted with respect to the sample normal. In-plane angular dependence of the ferromagnetic resonance (FMR) was used to obtain the relevant magnetic anisotropies, such as uniaxial and exchange bias fields. The oblique deposition geometry employed has induced non-collinear easy axes of the two ferromagnetic (FM) layers, with high uniaxial field strengths. The symmetry shift of the angular dependence of the FMR resonances of the two FM layers gives us directly the angle between the easy axes of FM{sub 1} (Py) and FM{sub 2} (FeCo), which turned out to be the angle between two adjacent sputtering sources. The observations of the present study suggest that, by combining oblique deposition and appropriate angles of incidence of the deposition flux, the uniaxial (and unidirectional) axes of individual FM layers can be precisely engineered in spin valve fabrication.

  2. Influence of tungsten substitution and oxygen deficiency on the thermoelectric properties of CaMnO{sub 3??}

    SciTech Connect (OSTI)

    Thiel, Philipp; Eilertsen, James; Populoh, Sascha, E-mail: sascha.populoh@empa.ch; Saucke, Gesine; Shkabko, Andrey; Sagarna, Leyre; Karvonen, Lassi [Laboratory for Solid State Chemistry and Catalysis, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Döbeli, Max [Ion Beam Physics, Schafmattstrasse 20, ETH Hönggerberg, Swiss Federal Institute of Technology, CH-8093 Zürich (Switzerland); Weidenkaff, Anke [Laboratory for Solid State Chemistry and Catalysis, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Materials Chemistry, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, DE-70569 Stuttgart (Germany)

    2013-12-28T23:59:59.000Z

    Polycrystalline tungsten-substituted CaMn{sub 1?x}W{sub x}O{sub 3??} (0.00???x???0.05) powders were synthesized from a polymeric precursor, pressed and sintered to high density. The impact of tungsten substitution on the crystal structure, thermal stability, phase transition, electronic and thermal transport properties is assessed. Tungsten acts as an electron donator and strongly affects high-temperature oxygen stoichiometry. Oxygen vacancies form in the high figure-of-merit (ZT)-region starting from about T?=?1000?K and dominate the carrier concentration and electronic transport far more than the tungsten substitution. The analysis of the transport properties yields that in the investigated regime the band filling is sufficiently high to overcome barriers of polaron transport. Therefore, the Cutler-Mott approach describes the electrical transport more accurately than the Mott approach for small polaron transport. The lattice thermal conductivity near room temperature is strongly suppressed with increasing tungsten concentration due to mass-difference impurity scattering. A ZT of 0.25 was found for x?=?0.04 at 1225?K.

  3. Environmental TEM study of electron beam induced electro-chemistry of Pr????Ca????MnO? catalysts for oxygen evolution

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mildner, Stephanie; Zhu, Yimei; Beleggia, Marco; Mierwaldt, Daniel; Hansen, Thoma Willum; Wagner, Jakob Birkedal; Yazdi, Sadegh; Kasama, Takeshi; Ciston, Jim; Jooss, Christian

    2015-03-12T23:59:59.000Z

    Environmental Transmission Electron Microscopy (ETEM) studies offer great potential for gathering atomic scale information on the electronic state of electrodes in contact with reactants but also pose big challenges due to the impact of the high energy electron beam. In this article, we present an ETEM study of a Pr????Ca????MnO? (PCMO) thin film electro-catalyst for water splitting and oxygen evolution in contact with water vapor. We show by means of off-axis electron holography and electrostatic modeling that the electron beam gives rise to a positive electric sample potential due to secondary electron emission. The value of the electric potential dependsmore »on the primary electron flux, the sample -conductivity and grounding, and gas properties. We present evidence that two observed electro-chemical reactions are driven by a beam induced electrostatic potential of the order of a volt. The first reaction is an anodic electrochemical oxidation reaction of oxygen depleted amorphous PCMO which results in recrystallization of the perovskite structure. The second reaction is oxygen evolution which can be detected by the oxidation of a silane additive and formation of SiO2–x at catalytically active surfaces. Recently published in-situ XANES observation of subsurface oxygen vacancy formation during oxygen evolution at a positive potential [³²] is confirmed in this work. The quantification of beam induced potentials is an important step for future controlled electro-chemical experiments in an ETEM.« less

  4. Sol–gel synthesis of long-lasting phosphors CdSiO{sub 3}: Mn{sup 2+}, RE{sup 3+} (RE = Tb, Eu, Nd) and luminescence mechanism research

    SciTech Connect (OSTI)

    Qu, Xiaofei [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China)] [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China); Cao, Lixin, E-mail: caolixin@mail.ouc.edu.cn [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China)] [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China); Liu, Wei; Su, Ge; Wang, Pingping; Schultz, Isabel [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China)] [Institute of Materials Science and Engineering, Ocean University of China, Songling Road 238, Qingdao 266100, Shandong Province (China)

    2012-06-15T23:59:59.000Z

    Highlights: ? New long-lasting CdSiO{sub 3}: Mn{sup 2+}, RE{sup 3+} (RE = Tb, Eu, Nd) phosphors were synthesized by a sol–gel method. ? The afterglow performance of the CdSiO{sub 3}: Mn{sup 2+}, Eu{sup 3+} phosphor was the best. ? The role of RE{sup 3+} co-doped into the CdSiO{sub 3}: Mn{sup 2+} matrix was discussed in this paper. -- Abstract: Mn{sup 2+} and RE{sup 3+} (RE = Tb, Eu, Nd) co-doped CdSiO{sub 3} orange phosphors were prepared at 1050 °C by a sol–gel method. The phase and crystallinity of the synthesized materials were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The luminescence characteristics were analyzed using photoluminescence (PL) spectra, afterglow decay curves, long-lasting phosphorescence spectra, and thermoluminescence (TL) spectra. Due to the difference in co-doped rare earth ionic radii, it varied greatly in trap density and trap depth caused by the different defects deriving from RE{sup 3+} ions co-doping into the CdSiO{sub 3}: Mn{sup 2+} host. The afterglow intensity and time for these samples increased as follows: CdSiO{sub 3}: Mn{sup 2+}0.2%, Nd{sup 3+}0.8% < CdSiO{sub 3}: Mn{sup 2+}0.4%, Tb{sup 3+}0.8% < CdSiO{sub 3}: Mn{sup 2+}0.4%, Eu{sup 3+}0.3%. CdSiO{sub 3}: Mn{sup 2+}0.4%, Eu{sup 3+}0.3% had the best afterglow properties, which could be due to the proper traps formed by Eu{sup 3+} ions co-doping into the host. The role of RE{sup 3+} co-doped into the CdSiO{sub 3}: Mn{sup 2+} matrix and the possible long-lasting phosphorescence process was also discussed in this paper.

  5. The Influence of Heat-Treatment Temperature on the Cation Distribution of LiNi0.5Mn0.5O2 and Its Rate Capability in Lithium Rechargeable Batteries

    SciTech Connect (OSTI)

    N Yabuuchi; Y Lu; A Mansour; S Chen; Y Shao-Horn

    2011-12-31T23:59:59.000Z

    LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} samples were prepared from NiMnO{sub 3} and Li{sub 2}CO{sub 3} in a range of temperatures from 900 to 1050 C. Synchrotron X-ray diffraction analysis combined with X-ray absorption spectroscopy showed that LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} segregated into one major Ni{sup 2+}O-enriched phase and one minor Li{sub 2}Mn{sup 4+}O{sub 3}-enriched phase, where the extent of segregation decreased with increasing synthesis temperature from 900 to 1050 C. Scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy revealed that the segregated domains exist in individual particles. Although all of the LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} samples showed comparable specific capacity ({approx}200 mAh/g) and capacity retention at low current densities, the rate capability of LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} of 900 C is lower than that of LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} of 1000 C. As X-ray photoelectron spectroscopy analysis showed that all of the LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} samples had comparable surface chemistry, the higher rate capability of LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} of 1000 C can be attributed to reduced cation segregation of Ni{sup 2+}O-enriched domains in the layered structure of the major phase, having potentially faster lithium diffusion than that of LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} of 900 C.

  6. Structural characterization of the perovskite series Sr{sub 1?x}La{sub x}Ti{sub 0.5}Mn{sub 0.5}O{sub 3}

    SciTech Connect (OSTI)

    Qasim, Ilyas [School of Chemistry, The University of Sydney, Sydney, NSW 2006 (Australia); Kennedy, Brendan J., E-mail: B.Kennedy@chem.usyd.edu.au [School of Chemistry, The University of Sydney, Sydney, NSW 2006 (Australia)

    2013-04-15T23:59:59.000Z

    The perovskite-type compounds Sr{sub 1?x}La{sub x}Ti{sub 0.5}Mn{sub 0.5}O{sub 3}, x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 have been synthesized by solid-state methods, and their room temperature structures determined using X-ray synchrotron powder diffraction. The x=0.0 end member, SrMn{sub 0.5}Ti{sub 0.5}O{sub 3} is cubic in space group Pm3{sup ¯}m; there being no evidence for ordering of the Ti{sup 4+} and Mn{sup 4+} cations. We find that x=0.5 compound is rhombohedral in R3{sup ¯}c rather than orthorhombic as reported previously. Magnetic measurements suggest that both SrMn{sub 0.5}Ti{sub 0.5}O{sub 3} and Sr{sub 0.5}La{sub 0.5}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} are spin-glasses. - Graphical abstract: A cubic–rhombohedral phase-transition is observed cation disordered perovskites Sr{sub 1?x}La{sub x}Ti{sub 0.5}Mn{sub 0.5}O{sub 3}. Both end members are spin-glasses. Highlights: ? Structural studies of Sr{sub 1?x}La{sub x}Ti{sub 0.5}Nb{sub 0.5}O{sub 3} perovskites, show lack of long range Mn:Ti order. ? Magnetic properties indicative of spin-glass behavior. ? Changes of crystal structure from cubic to rhombohedral with increasing lanthanum content.

  7. Neutron Resonance Parameters of 55Mn from Reich-Moore Analysis of Recent Experimental Neutron Transmission and Capture Cross Sections

    SciTech Connect (OSTI)

    Derrien, Herve [ORNL] [ORNL; Leal, Luiz C [ORNL] [ORNL; Larson, Nancy M [ORNL] [ORNL; Guber, Klaus H [ORNL] [ORNL; Wiarda, Dorothea [ORNL] [ORNL; Arbanas, Goran [ORNL] [ORNL

    2008-01-01T23:59:59.000Z

    High-resolution neutron capture cross section measurements of 55Mn were recently performed at GELINA by Schillebeeckx et al. (2005) and at ORELA by Guber et al. (2007). The analysis of the experimental data was performed with the computer code SAMMY using the Bayesian approach in the resonance parameters representation of the cross sections. The neutron transmission data taken in 1988 by Harvey et al. (2007) and not analyzed before were added to the SAMMY experimental data base. More than 95% of the s-wave resonances and more than 85% of the p-wave resonances were identified in the energy range up to 125 keV, leading to the neutron strength functions S0 = (3.90 0.78) x 10-4 and S1 = (0.45 0.08) x 10-4. About 25% of the d-wave resonances were identified with a possible strength function of S2 = 1.0 x 10-4. The capture cross section calculated at 0.0253 eV is 13.27 b, and the capture resonance integral is 13.52 0.30 b. In the energy range 15 to 120 keV, the average capture cross section is 12% lower than Lerigoleur value and 25% smaller than Macklin value. GELINA and ORELA experimental capture cross sections show a background cross section not described by the Reich-Moore resonance parameters. Part of this background could be due to a direct capture component and/or to the missing d-wave resonances. The uncertainty of 10% on the average capture cross section above 20 keV is mainly due to the inaccuracy in the calculation of the background components.

  8. Comparison of structural and electrical properties of Co{sup 2+}doped Mn-Zn soft nano ferrites prepared via coprecipitation and hydrothermal methods

    SciTech Connect (OSTI)

    Anwar, Humaira, E-mail: merey_anwar@yahoo.com [Thermal Transport Laboratory, Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology, H-12, Islamabad (Pakistan); Maqsood, Asghari [Centre for Emerging Sciences, Engineering and Technology (CESET), I-10/3, Islamabad (Pakistan)

    2014-01-01T23:59:59.000Z

    Graphical abstract: - Highlights: • Coprecipitation and hydrothermal synthesis of Co{sup 2+} doped Mn-Zn ferrites. • Dielectric measurements at 3 MHz and 1 GHz frequencies. • Enhanced DC electrical resistivity for samples prepared from hydrothermal technique. • Impedance studies for the prepared samples showing major contribution due to grains. - Abstract: A series of Co doped Mn-Zn ferrites compounds with the formula Mn{sub 0.5}Zn{sub 0.5?x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.15, 0.25, 0.35 and 0.50) were successfully synthesized by polyethylene glycol-assisted coprecipitation and hydrothermal methods. The structural characterization of the samples was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). All the samples found to have cubic spinel structure. The average crystallite size of all nanoparticles were estimated using Scherrer's formula and found to lie between 10 and 25 ± 3 nm with small size distribution of particles prepared by hydrothermal method. The FTIR spectrum showed two absorption bands of tetrahedral and octahedral metal-oxygen sites. DC electrical resistivity varied from 4.12 × 10{sup 7} to 8.32 × 10{sup 10} ohm cm with cobalt doping. The dielectric measurements were performed from 20 Hz to 3 MHz and from 1 MHz to 1 GHz frequency ranges. The value of dielectric constant (??) varies from 15.54 to 106.25 (1 MHz) and 6.73–16.48 (1 GHz) for all the samples at room temperature. Impedance spectroscopy was carried out from 20 Hz to 3 MHz, at room temperature to study the grains and grain boundaries effect.

  9. Magnetic phase transitions and entropy change in layered NdMn{sub 1.7}Cr{sub 0.3}Si{sub 2}

    SciTech Connect (OSTI)

    Md Din, M. F., E-mail: mfmd999@uowmail.edu.au; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522 (Australia); Wang, J. L. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Campbell, S. J. [School of Physical, Environmental, and Mathematical Sciences, The University of New South Wales, Canberra, The Australian Defence Force Academy, Australian Capital Territory 2600 (Australia); Studer, A. J.; Avdeev, M.; Kennedy, S. J. [Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Gu, Q. F. [Australian Synchrotron, 800 Blackburn Rd, Clayton 3168 (Australia); Zeng, R. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522 (Australia); Solar Energy Technologies, School of Computing, Engineering and Mathematics, University of Western Sydney, Penrith, NSW 2751 (Australia)

    2014-01-27T23:59:59.000Z

    A giant magnetocaloric effect has been observed around the Curie temperature, T{sub C}???42?K, in NdMn{sub 1.7}Cr{sub 0.3}Si{sub 2} with no discernible thermal and magnetic hysteresis losses. Below 400?K, three magnetic phase transitions take place around 380?K, 320?K and 42?K. Detailed high resolution synchrotron and neutron powder diffraction (10–400?K) confirmed the magnetic transitions and phases as follows: T{sub N}{sup intra}???380?K denotes the transition from paramagnetism to intralayer antiferromagnetism (AFl), T{sub N}{sup inter}???320?K represents the transition from the AFl structure to the canted antiferromagnetic spin structure (AFmc), while T{sub C}???42?K denotes the first order magnetic transition from AFmc to canted ferromagnetism (Fmc?+?F(Nd)) due to ordering of the Mn and Nd sub-lattices. The maximum values of the magnetic entropy change and the adiabatic temperature change, around T{sub C} for a field change of 5?T are evaluated to be ??S{sub M}{sup max}???15.9?J kg{sup ?1} K{sup ?1} and ?T{sub ad}{sup max}???5?K, respectively. The first order magnetic transition associated with the low levels of hysteresis losses (thermal Mn{sub 1.7}Cr{sub 0.3}Si{sub 2} offers potential as a candidate for magnetic refrigerator applications in the temperature region below 45?K.

  10. Insight into cation disorder of Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4}

    SciTech Connect (OSTI)

    Bini, Marcella [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy); Ferrari, Stefania, E-mail: stefania.ferrari@unipv.it [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy); Capsoni, Doretta; Spreafico, Clelia; Tealdi, Cristina; Mustarelli, Piercarlo [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy)

    2013-04-15T23:59:59.000Z

    Transition metal lithium orthosilicates are promising cathode materials for lithium-ion batteries. Here we report a combined experimental (in situ X-ray diffraction) and computational (static lattice and molecular dynamics) study of the thermal behavior of the Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4} orthosilicate from room temperature to 950 °C. Our X-ray results showed that Pmnb polymorph is the most stable all over the explored temperature range. A significant cation disorder up to 80%, based on the anti-site defect, was found. The defect concentration depends on the synthesis route and temperature, and is completely reversible after the thermal treatments. Moreover, a careful analysis of the impurity phases allowed us to identify Li{sub 2}SiO{sub 3}, Fe{sub 3}O{sub 4} and Li{sub 3}Fe{sub 5}O{sub 8}, the last one never reported before. The minimization of defects by opportunely tuning the synthetic parameters would be of great importance in view of potential applications of these materials in lithium batteries. - Graphical abstract: A combined experimental in situ X-ray diffraction and computational study of the thermal behavior of the Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4} is reported herein. The anti-site defect does justify the diffraction patterns changes with temperature. Highlights: ? Study of the thermal behavior of Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4}. ? The anti-site defect does justify the diffraction patterns changes with temperature. ? The Pmnb polymorph is stable in the investigated temperaturerange.

  11. A neutron diffraction study of the magnetic structure for the perovskite-type mixed oxides La(Mn, Cr)03 and (La, Sr)Fe03

    E-Print Network [OSTI]

    Bents, Ulrich H.

    1956-01-01T23:59:59.000Z

    A NEUTRON DIFFRACTION STUDY OF THE MAGNETIC STRUCTURE FOR THE PEROVSKITE-TYPE MIXED OXIDES La(Mn,Cr)03 AND (La,Sr)Fe03 A Dissertation By ULRICH H. BENTS Submitted to the Graduate School of the Agricultural and Mechanical College of Texas... in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 1956 Major Subjectj Physics l i b r a r y l A i braayb?y r? ???l? A NEUTRON DIFFRACTION STUDY OF THE MAGNETIC STRUCTURE FOR THE PEROVSKITE-TYPE MIXED OXIDES La...

  12. Magnetic depth profile of a modulation doped La{sub 1-x}Ca{sub x}MnO{sub 3} exchange-biased system.

    SciTech Connect (OSTI)

    Hoffmann, A.; May, S. J.; teVelthuis, S. G. E.; Park, S.; Fitzsimmons, M. R.; Campillo, G.; Gomez, M. E.; LANL; Pusan National Univ.; Universidad del Valle; Universidad Autonoma de Madrid

    2009-01-01T23:59:59.000Z

    Recent magnetometry measurements in modulation-doped La{sub 1-x}Ca{sub x}MnO{sub 3} suggested that a net magnetization extends from the ferromagnetic layers into the adjacent antiferromagnet layers. Here we test this hypothesis by polarized neutron reflectometry, which allows us to determine the depth resolved magnetization profile. From fits to the reflectivity data we find that the additional magnetization does not occur at the ferromagnetic/antiferromagnetic interfaces, but rather in a thin region of the first antiferromagnetic layer adjacent to the interface with the substrate.

  13. The features of structural transformations in lanthanum manganites La{sub 1?x}A{sub x}MnO{sub 3+?} (A = Ca, Sr, Ba)

    SciTech Connect (OSTI)

    Sedykh, Vera D., E-mail: sedykh@issp.ac.ru [Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka (Russian Federation)

    2014-10-27T23:59:59.000Z

    In this work, the effect of the ionic radius and concentration of a doping element on the features of the structural transformations in polycrystalline lanthanum manganites, La{sub 1?x}A{sub x}MnO{sub 3+?} (A = Ca, Sr, Ba), has been studied by Mössbauer spectroscopy and X-ray diffraction analysis. For Mössbauer investigations, a small amount of {sup 57}Fe (2 at%) Mössbauer isotope was introduced into the samples. It follows from the analysis of the obtained data that both common features of the structural transformations and differences between them exist in lanthanum manganites depending on ionic radius and concentration of a doping element.

  14. Structural phase transition and electrode characteristics of LiMn{sub 2{minus}x}Mg{sub x}O{sub 4} positive electrode material for the lithium secondary battery

    SciTech Connect (OSTI)

    Idemoto, Y.; Udagawa, K.; Koura, N.; Richardson, J. W., Jr.; Takeuchi, K.; Loong, C.-K.

    1999-12-10T23:59:59.000Z

    With in mind improving the cycle performance of 4V class lithium manganese oxide positive electrode material for the lithium secondary battery, the authors have been investigating the effects of partial substitution of Mn by another metal. The crystal phase transition in the quaternary spinel LiMn{sub 2{minus}x}Mg{sub x}O{sub 4} was studied by neutron powder diffraction at 200K and DSC measurements at low temperatures. They find that substituting Mn by Mg resulted in a more stable crystal structure with the Jahn-Teller transition suppressed down to low temperature. The charge-discharge characteristics of these positive electrode active materials were investigated at 4V range. Although the discharge capacity decreased with increasing Mg content, the cycle performance was improved with increasing Mg content.

  15. Effects of Nb doping level on the electronic transport, photoelectric effect and magnetoresistance across La{sub 0.5}Ca{sub 0.5}MnO{sub 3}/Nb:SrTiO{sub 3} junctions

    SciTech Connect (OSTI)

    Wang, J. F., E-mail: jifewang@gmail.com [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); College of Science, China Jiliang University, Hangzhou, Zhejiang 310018 (China); Jiang, Y. C.; Gao, J., E-mail: jugao@hku.hk [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Chen, M. G. [College of Science, China Jiliang University, Hangzhou, Zhejiang 310018 (China)] [College of Science, China Jiliang University, Hangzhou, Zhejiang 310018 (China)

    2013-12-16T23:59:59.000Z

    Heterojunctions composed of La{sub 0.5}Ca{sub 0.5}MnO{sub 3} and Nb doped SrTiO{sub 3} were fabricated, and the effects of the Nb doping level on their electronic transport, photoelectric effect, and magnetoresistance were investigated. A lower doping concentration of Nb led to better rectifying properties and higher open circuit voltages. The I-V curves for La{sub 0.5}Ca{sub 0.5}MnO{sub 3}/0.7?wt.?% Nb-SrTiO{sub 3} showed a negligible response to magnetic fields for all temperatures, whereas La{sub 0.5}Ca{sub 0.5}MnO{sub 3}/0.05?wt.?% Nb-SrTiO{sub 3} exhibited distinct magnetoresistance, which depended on both the bias voltage and temperature. These results are discussed with the assistance of conventional semiconductor theories.

  16. Enhancement of spin polarization via Fermi level tuning in Co{sub 2}MnSn{sub 1?x}Sb{sub x} (x = 0, 0.25. 0.5, 0.75, 1) Heusler alloys

    SciTech Connect (OSTI)

    Singh, Mukhtiyar, E-mail: msphysik09@gmail.com; Thakur, Jyoti; Kashyap, Manish K. [Department of Physics, Kurukshetra University, Kurukshetra - 136119, Haryana (India); Saini, Hardev S. [Department of Physics, National Institute of Technology, Kurukshetra - 136119, Haryana (India)

    2014-04-24T23:59:59.000Z

    Full potential approach has been employed to tune Fermi level in Co{sub 2}MnSn{sub 1?x}Sb{sub x} (x = 0, 0.25, 0.5, 0.75, 1) Heulser alloys for enhancement of spin polarization and finding signature of half metallicity. Present density functional theory (DFT) based calculation indicates that stoichoimetric Heusler alloy, Co{sub 2}MnSn is not a half-metallic ferromagnet but the doping of Sb in it results in the shifting of E{sup F} in well-defined energy gap which leads the 100% spin polarization in the resultant alloys. The magnetism in present alloys is governed by localized moment on Mn atom mainly. The tuning of half-metallicity using doping can be proved as an ideal technique to search the new materials which can accomplish the need of spintronics.

  17. Spin waves throughout the Brillouin zone and magnetic exchange coupling in ferromagnetic metallic manganites La$_{1-x}$Ca$_{x}$MnO$_3$ ($x=0.25,0.30$)

    SciTech Connect (OSTI)

    Ye, Feng [ORNL; Dai, Pengcheng [ORNL; Fernandez-Baca, Jaime A [ORNL; Adroja, D. T. [ISIS Facility, Rutherford Appleton Laboratory; Perring, T. G. [ISIS Facility, Rutherford Appleton Laboratory; Tomioka, Y. [Correlated Electron Research Center (CERC), Japan; Tokura, Y. [University of Tokyo, Tokyo, Japan

    2007-01-01T23:59:59.000Z

    Using time-of-flight and triple-axis inelastic neutron spectroscopy, we determine spin wave excitations throughout the Brillouin zone for ferromagnetic manganites La$_{1-x}$Ca$_x$MnO$_3$ ($x=0.25,0.3$) in their low temperature metallic states. While spin wave excitations in the long wavelength limit (spin stiffness $D$) have similar values for both compounds, the excitations near the Brillouin zone boundary of La$_{0.7}$Ca$_{0.3}$MnO$_3$ are considerable softened in all symmetry directions compared to that of La$_{0.75}$Ca$_{0.25}$MnO$_3$. A Heisenberg model with the nearest neighbor and the fourth neighbor exchange interactions can describe the overall dispersion curves fairly well. We compare the data with various theoretical models describing the spin excitations of ferromagnetic manganites.

  18. Spin waves throughout the Brillouin zone and magnetic exchange coupling in the ferromagnetic metallic manganites La1?xCaxMnO3 (x=0.25, 0.30)

    SciTech Connect (OSTI)

    Ye, Feng [ORNL; Dai, Pengcheng [ORNL; Fernandez-Baca, Jaime A [ORNL; Adroja, D. T. [ISIS Facility, Rutherford Appleton Laboratory; Perring, T. G. [ISIS Facility, Rutherford Appleton Laboratory; Tomioka, Y. [Correlated Electron Research Center (CERC), Japan; Tokura, Y. [University of Tokyo, Tokyo, Japan

    2007-01-01T23:59:59.000Z

    Using time-of-flight and triple-axis inelastic neutron spectroscopy, we determine spin-wave excitations throughout the Brillouin zone for ferromagnetic manganites La1?xCaxMnO3 (x=0.25, 0.3) in their lowtemperature metallic states. While spin-wave excitations in the long-wavelength limit spin stiffness D have similar values for both compounds, the excitations near the Brillouin-zone boundary of La0.7Ca0.3MnO3 are considerably softened in all symmetry directions compared to that of La0.75Ca0.25MnO3. A Heisenberg model with the nearest neighbor and the fourth neighbor exchange interactions can describe the overall dispersion curves fairly well. We compare the data with various theoretical models describing the spin excitations of ferromagnetic manganites.

  19. Phase evolution and magnetocaloric effect of melt-spun Mn{sub 3}Sn{sub 2-xM{sub x}} (M = B, C; x = 0-0.5) ribbons

    SciTech Connect (OSTI)

    Zhao, X. G. [Department of Physics, National Chung Cheng University, Ming Hsiung, Chia-Yi 62102, Taiwan (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Lee, E. H.; Hsieh, C. C.; Shih, C. W.; Chang, W. C. [Department of Physics, National Chung Cheng University, Ming Hsiung, Chia-Yi 62102, Taiwan (China); Zhang, Z. D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, and International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China)

    2012-04-01T23:59:59.000Z

    The effects of B and C substitution for Sn on phase components, Curie temperature T{sub C}, and magnetocaloric effect of melt-spun Mn{sub 3}Sn{sub 2-x}M{sub x} (M B, C; x = 0-0.5) ribbons have been investigated. X-ray diffraction (XRD) results show that the main phase in the as-spun Mn{sub 3}Sn{sub 2-xM{sub x}} (M = B, C; x 0-0.5) ribbons is Mn{sub 3}Sn{sub 2} of Ni{sub 3}Sn{sub 2}-type (Pnma). Minor Mn{sub 2}B (when x {>=} 0.1) or Mn{sub 5}C{sub 2} (when x > 0.1) secondary phase is formed, and their amounts increase with increasing B and C concentration, respectively. The Curie temperature T{sub C} of these ribbons varies in the temperature range of 240-250 K. The peak values of the maximal magnetic entropy change, -{Delta}S{sub M}{sup max}, are about 13.6-18.3 mJ/cm{sup 3} K for B-substituted ribbons and 13.6-17.5 mJ/cm{sup 3} K for C-substituted ribbons, respectively, at a maximum applied field of 50 kOe. These values are about one fifth that of Gd (81.4 mJ/cm{sup 3} K). However, the relatively broader temperature range of the half maximum of {Delta}S{sub M} peak ({approx}100 K), low-cost and nontoxic elements still make Mn{sub 3}Sn{sub 2}-based ribbons the promising candidates for magnetic refrigeration applications close to room temperature.

  20. Breakdown by magnetic field in a La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/MgO/Fe spin valve

    SciTech Connect (OSTI)

    Wu Xiaojie; Meng Jian [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); Zhang Zhenzhong [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dongnanhu Road, Changchun 130033 (China)

    2012-03-19T23:59:59.000Z

    A La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/MgO/Fe spin valve with inverse tunneling magnetoresistance (TMR) was fabricated on a (100) SrTiO{sub 3} substrate by radio frequency magnetron sputtering. Giant TMR ratios up to 540% were obtained. The breakdown of the spin valve was observed at high magnetic field, which was attributed to the joint action of the invalidation of MgO barrier and the shift of Fermi energy in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} at high magnetic field.

  1. Ferromagnetism and magneto-transport properties of Mn{sub 0.92}Ca{sub 0.08}As thin film grown on Al{sub 2}O{sub 3}(0001) substrate

    SciTech Connect (OSTI)

    Dung, Dang Duc; Van Thiet, Duong [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); Anh Tuan, Duong; Cho, Sunglae, E-mail: slcho@ulsan.ac.kr [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Feng, Wuwei [School of Materials Science and Engineering, China University of Geosciences, Beijing 100083 (China)

    2014-05-07T23:59:59.000Z

    The epitaxial Mn{sub 0.92}Ca{sub 0.08}As thin film was grown on Al{sub 2}O{sub 3}(0001) substrate by molecular beam epitaxy. The Curie temperature (T{sub C}) around 340?K was enhanced with the addition of Ca, compared to that of bulk MnAs (T{sub C}???318?K). The maxima magnetoresistance, ?2.08% at 0.7?T, was observed near the critical magnetic transition temperature. Moreover, the giant magnetocaloric effect was found with the maximum magnetic entropy change, ?200?J/kgK, around 330?K at 5?T.

  2. Giant magnetocaloric effect of Mn{sub 0.92}Ba{sub 0.08}As thin film grown on Al{sub 2}O{sub 3}(0001) substrate

    SciTech Connect (OSTI)

    Dang Duc Dung [Department of Physics, University of Ulsan, Ulsan 690-749 (Korea, Republic of); Department of General Physics, School of Engineering, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); Duong Anh Tuan; Duong Van Thiet; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 690-749 (Korea, Republic of)

    2012-04-01T23:59:59.000Z

    The epitaxial Mn{sub 0.92}Ba{sub 0.08}As thin film was grown on Al{sub 2}O{sub 3}(0001) substrate by molecular beam epitaxy. The Curie temperature (T{sub C}) around 350 K was enhanced with the addition of Ba, compared to that of bulk MnAs (T{sub C} {approx} 318 K). We have observed the linear resistivity versus the square of temperature and high negative magnetoresistance near Curie temperature. Moreover, the giant magnetocaloric effect was found with maximum magnetic entropy change, 65 J/kgK, around room temperature at 5 T.

  3. Thermal chemistry of Mn{sub 2}(CO){sub 10} during deposition of thin manganese films on silicon oxide and on copper surfaces

    SciTech Connect (OSTI)

    Qin Xiangdong; Sun Huaxing; Zaera, Francisco [Department of Chemistry, University of California, Riverside, California 92521 (United States)

    2012-01-15T23:59:59.000Z

    The surface chemistry of dimanganese decacarbonyl on the native oxide of Si(100) wafers was characterized with the aid of x-ray photoelectron spectroscopy. Initial experiments in a small stainless-steel reactor identified a narrow range of temperatures, between approximately 445 and 465 K, in which the deposition of manganese could be achieved in a self-limiting fashion, as is desirable for atomic layer deposition. Deposition at higher temperatures leads to multilayer growth, but the extent of this Mn deposition reverses at even higher temperatures (about 625 K), and also ifhydrogen is added to the reaction mixture. Extensive decarbonylation takes place below room temperature, but limited C-O bond dissociation and carbon deposition are still seen after high exposures at 625 K. The films deposited at low ({approx}450 K) temperatures are mostly in the form of MnO, but at 625 K that converts to a manganese silicate, and upon higher doses a manganese silicide forms at the SiO{sub 2}/Si(100) interface as well. No metallic manganese could be deposited with this precursor on either silicon dioxide or copper surfaces.

  4. Octahedral distortion induced magnetic anomalies in LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals

    SciTech Connect (OSTI)

    Manna, Kaustuv, E-mail: kaustuvmanna@gmail.com; Elizabeth, Suja; Anil Kumar, P. S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Bhadram, Venkata Srinu; Narayana, Chandrabhas [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2014-07-28T23:59:59.000Z

    Single crystals of LaMn{sub 0.5}Co{sub 0.5}O{sub 3} belonging to the ferromagnetic-insulator and distorted perovskite class were grown using a four-mirror optical float zone furnace. The as-grown crystal crystallizes into an orthorhombic Pbnm structure. The spatially resolved 2D Raman scan reveals a strain-induced distribution of transition metal (TM)–oxygen (O) octahedral deformation in the as-grown crystal. A rigorous annealing process releases the strain, thereby generating homogeneous octahedral distortion. The octahedra tilt by reducing the bond angle TM-O-TM, resulting in a decline of the exchange energy in the annealed crystal. The critical behavior is investigated from the bulk magnetization. It is found that the ground state magnetic behavior assigned to the strain-free LaMn{sub 0.5}Co{sub 0.5}O{sub 3} crystal is of the 3D Heisenberg kind. Strain induces mean field-like interaction in some sites, and consequently, the critical exponents deviate from the 3D Heisenberg class in the as-grown crystal. The temperature-dependent Raman scattering study reveals strong spin-phonon coupling and the existence of two magnetic ground states in the same crystal.

  5. Effects of the interplay between atomic and magnetic order on the properties of metamagnetic Ni-Co-Mn-Ga shape memory alloys

    SciTech Connect (OSTI)

    Seguí, C., E-mail: concepcio.segui@uib.es [Departament de Física, Universitat de les Illes Balears, Campus universitari. Cra. de Valldemossa km 7.5, 07122 Palma de Mallorca (Spain)

    2014-03-21T23:59:59.000Z

    Ni-Co-Mn-Ga ferromagnetic shape memory alloys show metamagnetic behavior for a range of Co contents. The temperatures of the structural and magnetic transitions depend strongly on composition and atomic order degree, in such a way that combined composition and thermal treatment allows obtaining martensitic transformation between any magnetic state of austenite and martensite. This work presents a detailed analysis of the effect of atomic order on Ni-Co-Mn-Ga alloys through the evolution of structural and magnetic transitions after quench from high temperatures and during post-quest ageing. It is found that the way in which the atomic order affects the martensitic transformation temperatures and entropy depends on the magnetic order of austenite and martensite. The results can be explained assuming that improvement of atomic order decreases the free energy of the structural phases according to their magnetic order. However, it is assumed in this work that changes in the slope—that is, the entropy—of the Gibbs free energy curves are also decisive to the stability of the two-phase system. The experimental transformation entropy values have been compared with a phenomenological model, based on a Bragg–Williams approximation, accounting for the magnetic contribution. The excellent agreement obtained corroborates the magnetic origin of changes in transformation entropy brought about by atomic ordering.

  6. Single crystal neutron diffraction study of lattice and magnetic structures of 5M modulated Ni2Mn1.14Ga0.86

    SciTech Connect (OSTI)

    Pramanick, Abhijit [ORNL] [ORNL; Wang, Xiaoping [ORNL] [ORNL; An, Ke [ORNL] [ORNL; Stoica, Alexandru Dan [ORNL] [ORNL; Hoffmann, Christina [ORNL] [ORNL; Wang, Xun-Li [ORNL] [ORNL

    2012-01-01T23:59:59.000Z

    A comprehensive description of the crystal and magnetic structures of Ni-Mn-Ga magnetic shape memory alloys is important to understand the physical origins of their magnetoelastic properties. These structural details for an off-stoichiometric Ni2Mn1.14Ga0.86 alloy have been obtained from refinement of high-resolution single crystal neutron diffraction data following a (3+1)-dimensional superspace formalism. In particular, the structure adopts a P2/m( 0 )00 (3+1)-D superspace symmetry with the following fundamental lattice parameters: a=4.255(4) , b=5.613(4) , c=4.216(3) , a commensurate periodicity of 5M and a modulation wave vector of . The magnetic moments are aligned along the b-axis. The modulations for atomic site displacements, site occupancies and magnetic moments are elucidated from a (3+1)-D refinement of the neutron diffraction data. In addition to atomic displacements corresponding to shear waves along <110>, distortions of Ni-centric tetrahedra are also evident. Physical interpretations for the different structural distortions and their relationship with magnetic properties are discussed.

  7. Room temperature ferromagnetic and ferroelectric properties of Bi{sub 1?x}Ca{sub x}MnO{sub 3} thin films

    SciTech Connect (OSTI)

    Pugazhvadivu, K. S.; Tamilarasan, K., E-mail: dr.k.tamilarasan@gmail.com [Thin Film Laboratory, Department of Physics, Kongu Engineering College, Perundurai - 638 052 (India); Balakrishnan, L. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore - 632 014 (India); Mohan Rao, G. [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore - 560 012 (India)

    2014-11-15T23:59:59.000Z

    Bi{sub 1?x}Ca{sub x}MnO{sub 3} (BCMO) thin films with x = 0, 0.1, 0.2, 0.3 and 0.4 are successfully deposited on the n-type Si (100) substrate at two different temperatures of 400 °C and 800 °C using RF magnetron sputtering. The stoichiometry of the films and oxidation state of the elements have been described by X-ray photoelectron spectroscopy analysis. Dielectric measurement depicts the insulating property of BCMO films. Magnetic and ferroelectric studies confirm the significant enhancement in spin orientation as well as electric polarization at room temperature due to incorporation of Ca{sup 2+} ions into BiMnO{sub 3} films. The BCMO (x = 0.2) film grown at 400 °C shows better magnetization (M{sub sat}) and polarization (P{sub s})with the measured values of 869 emu / cc and 6.6 ?{sub C}/ cm{sup 2} respectively than the values of the other prepared films. Thus the realization of room temperature ferromagnetic and ferroelectric ordering in Ca{sup 2+} ions substituted BMO films makes potentially interesting for spintronic device applications.

  8. Pressure effects on magnetic pair-breaking in Mn- and Eu-substituted BaFe{sub 2}As{sub 2}

    SciTech Connect (OSTI)

    Rosa, P. F. S., E-mail: ferrari@ifi.unicamp.br [Instituto de Física “Gleb Wataghin,” UNICAMP, Campinas-SP 13083-859 (Brazil); University of California, Irvine, California 92697-4574 (United States); Garitezi, T. M.; Adriano, C.; Urbano, R. R.; Pagliuso, P. G. [Instituto de Física “Gleb Wataghin,” UNICAMP, Campinas-SP 13083-859 (Brazil); Grant, T.; Fisk, Z. [University of California, Irvine, California 92697-4574 (United States); Fernandes, R. M. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2014-05-07T23:59:59.000Z

    We report a combined study of hydrostatic pressure (P ? 25 kbar) and chemical substitution on the magnetic pair-breaking effect in Eu- and Mn-substituted BaFe{sub 2}As{sub 2} single crystals. At ambient pressure, both substitutions suppress the superconducting (SC) transition temperature (T{sub c}) of BaFe{sub 2–x}Co{sub x}As{sub 2} samples slightly under the optimally doped region, indicating the presence of a pair-breaking effect. At low pressures, an increase of T{sub c} is observed for all studied compounds followed by an expected decrease at higher pressures. However, in the Eu dilute system, T{sub c} further increases at higher pressure along with a narrowing of the SC transition, suggesting that a pair-breaking mechanism reminiscent of the Eu Kondo single impurity regime is being suppressed by pressure. Furthermore, Electron Spin Resonance (ESR) measurements indicate the presence of Mn{sup 2+} and Eu{sup 2+} local moments and the microscopic parameters extracted from the ESR analysis reveal that the Abrikosov–Gor'kov expression for magnetic pair-breaking in a conventional sign-preserving superconducting state cannot describe the observed reduction of T{sub c}.

  9. M;N

    E-Print Network [OSTI]

    Article Submitted to Journal of Symbolic Computation. Algorithmic strati cation of R H om. D(M; N). for regular algebraic D-modules on C. n. Uli Walther.

  10. Team OptiMN

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn April 23,EnergyChicopee ElectricCommunity-Based EnergyNWSmallTaxUniversity of Minnesota

  11. arXiv:1201.0642v1[astro-ph.GA]3Jan2012 Mon. Not. R. Astron. Soc. 000, 000000 (0000) Printed 4 January 2012 (MN LATEX style file v2.2)

    E-Print Network [OSTI]

    Henning, Thomas

    January 2012 (MN LATEX style file v2.2) Stochastic grain heating and mid-infrared emission in protostellar and compared with observations of a representative infrared dark cloud core. We show that stochastic heating heating of small grains is often mentioned as a primary cause of large in- frared (IR) fluxes from star

  12. Enhanced Jahn-Teller response induced by low-dose 10?MeV I{sup +} irradiation of La{sub 0.7}Ca{sub 0.3}MnO{sub 3??} films

    SciTech Connect (OSTI)

    Harris, V. G., E-mail: v.harris@neu.edu; Chen, Y. [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Byers, J. M.; Stroud, R. M.; Osofsky, M. S.; Knies, D.; Grabowski, K. S. [U.S. Naval Research Laboratory, Code 6360, Washington, DC 20375 (United States); Browning, V. M.; Fuller-Mora, W. W. [U.S. Naval Research Laboratory, Code 6340, Washington, DC 20375 (United States); Kim, J. [Neocera, LLC, 10000 Virginia Manor Road, Beltsville, Maryland 20705 (United States)

    2014-05-26T23:59:59.000Z

    The structural response of pulsed laser deposited La{sub 0.7}Ca{sub 0.3}Mn0{sub 3??} films to low-level 10?MeV I{sup +} irradiation is correlated with magnetic and electronic properties. A series of annealed pulsed laser deposited films were subjected to ion irradiation at doses of 0.5–2.0 × 10{sup 13} 10?MeV iodine ions/cm{sup 2}. X-ray diffraction measurements show no measurable increase in the full width at half maximum values of major reflections before and after irradiation. Extended x-ray absorption fine structure analyses (EXAFS), employing both a model independent fitting using expanded cumulants as well as a nonlinear least squares multiple scattering model based on FEFF generated theoretical EXAFS data, were employed to measure local properties relative to the Mn ions. Increasing irradiation doses lead to an unambiguous evolution of MnO{sub 6} octahedra from highly symmetric (i.e., undistorted) to a clear bimodal structure in which the MnO{sub 6} octahedra are measured to undergo a c-axis stretching bearing resemblance to a Jahn-Teller distortion. Concomitantly, the metal to insulator transition temperature decreases more than 270?K and the magnetoresistance increases from 10{sup 2}% to 10{sup 6}%.

  13. Mon. Not. R. Astron. Soc. 000, 114 (2008) Printed 10 January 2009 (MN LATEX style file v2.2) High-energy particle acceleration at the radio-lobe shock of

    E-Print Network [OSTI]

    Evans, Dan

    2008-01-01T23:59:59.000Z

    Mon. Not. R. Astron. Soc. 000, 1­14 (2008) Printed 10 January 2009 (MN LATEX style file v2.2) HighTT, UK 8 Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA, 22904

  14. Mon. Not. R. Astron. Soc. XXX, XXX--XXX (1999) Printed 15 December 1999 (MN plain T E X macros v1.6) Development of structure in pores and sunspots: flows

    E-Print Network [OSTI]

    Rucklidge, Alastair

    1999-01-01T23:59:59.000Z

    Mon. Not. R. Astron. Soc. XXX, XXX--XXX (1999) Printed 15 December 1999 (MN plain T E X macros v1.M.Rucklidge@damtp.cam.ac.uk http://www.damtp.cam.ac.uk/user/alastair Received XXX; in original form 1999 June 16 ABSTRACT Flux

  15. Structural Underpinnings of the Enhanced Cycling Stability upon Al-Substitution in LiNi0.45Mn0.45Co0.1-yAlyO2 Positive Electrode Materials for Li-ion Batteries

    E-Print Network [OSTI]

    Conry, Thomas E.

    2013-01-01T23:59:59.000Z

    materials for Li-ion batteries Thomas E. Conry, a,b Apurvamaterials in Li-ion batteries. Synchrotron-based high-materials for Li-ion batteries. LiNi z Mn z Co 1-2z O 2 (NMC

  16. In-situ high-energy x-ray diffuse-scattering study of the phase transition in a Ni{sub 2}MnGa ferromagnetic shape-memory crystal.

    SciTech Connect (OSTI)

    Wang, G.; Yan-Dong, W.; Yang, R.; Yan-Dong, L.; Peter, L. K.; X-Ray Science Division; Northeastern Univ.; Univ. of Tennessee

    2008-12-01T23:59:59.000Z

    The full information on the changes in many crystallographic aspects, including the structural and microstructural characterizations, during the phase transformation is essential for understanding the phase transition and 'memory' behavior in the ferromagnetic shape-memory alloys. In the present article, the defects-related microstructural features connected to the premartensitic and martensitic transition of a Ni{sub 2}MnGa single crystal under a uniaxial pressure of 50 MPa applied along the [110] crystallographic direction were studied by the in-situ high-energy X-ray diffuse-scattering experiments. The analysis of the characteristics of diffuse-scattering patterns around different sharp Bragg spots suggests that the influences of some defect clusters on the pressure-induced phase-transition sequences of Ni2MnGa are significant. Our experiments show that an intermediate phase is produced during the premartensitic transition in the Ni{sub 2}MnGa single crystal, which is favorable for the nucleation of a martensitic phase. The compression stress along the [110] direction of the Heusler phase can promote the premartensitic and martensitic transition of the Ni{sub 2}MnGa single crystal.

  17. Site-specific local structure of Mn in artificial manganese ferrite films E. Kravtsov,1,2 D. Haskel,1 A. Cady,1 A. Yang,3 C. Vittoria,3 X. Zuo,4 and V. G. Harris3

    E-Print Network [OSTI]

    Haskel, Daniel

    Site-specific local structure of Mn in artificial manganese ferrite films E. Kravtsov,1,2 D. Haskel in manganese ferrite films grown under nonequilibrium conditions. The DAFS spectra were measured at a number. INTRODUCTION There has been considerable long-term interest in spinel ferrite materials due

  18. Phase Transitions in the LiNi0.5Mn0.5O2 System with Temperature Yoyo Hinuma, Ying S. Meng, Kisuk Kang, and Gerbrand Ceder*

    E-Print Network [OSTI]

    Ceder, Gerbrand

    of the energy on the arrangement of Li+ , Ni2+ , and Mn4+ in the lithium layer and transition metal layer. First represents magnetic interactions than standard GGA. The simulation results suggest two phase with this material. Other properties of the material, such as thermal stability and safety, have also been

  19. Evidence for anisotropic triplet superconductor order parameter in half metallic ferromagnetic La_0.7Ca_0.3MnO_3 proximity coupled to superconducting Pr_1.85Ce_0.15CuO_4

    E-Print Network [OSTI]

    Kalcheim, Y.; Millo, O.; Egilmez, M.; Robinson, J. W. A.; Blamire, M. G.

    2012-03-07T23:59:59.000Z

    Scanning tunneling spectroscopy measurements performed on La_0.7Ca_0.3MnO_3 (LCMO) films epitaxially grown on Pr_1.85Ce_0.15CuO_4 (PCCO) reveal localized penetration of superconductivity into the LCMO up to distances much larger than is possible...

  20. GaGa11--xxMnMnxxAsAs11--yyTeTeyy Synthesized bySynthesized by Ion Implantation & Pulsed Laser MeltingIon Implantation & Pulsed Laser Melting

    E-Print Network [OSTI]

    Priour, Don - Department of Physics, University of Missouri

    ] · stabilizing EF by compensation might allow higher MnGa add Te · experiment possible using II-PLM no chamber Implantation & Pulsed Laser Melting (IIPulsed Laser Melting (II--PLM)PLM) Excimer Laser Pulse GaAs Liquid Melt, NATURE MATERIALS 1 185 (2002) [4] Scarpulla, PHYSICA B 340 908 (2003) #12;IIII--PLM GaPLM Ga11--xx

  1. Origin and tuning of the magnetocaloric effect in the magnetic refrigerant Mn1.1Fe0.9(P0.8Ge0.2) Danmin Liu,1,2

    E-Print Network [OSTI]

    Lynn, Jeffrey W.

    Origin and tuning of the magnetocaloric effect in the magnetic refrigerant Mn1.1Fe0.9(P0.8Ge0, magnetic refrigeration at ambient temperatures has attracted interest with the discovery of new materials December 2008; published 26 January 2009 Neutron-diffraction and magnetization measurements have been

  2. arXiv:1002.0800v1[astro-ph.GA]3Feb2010 Mon. Not. R. Astron. Soc. 000, 000000 (0000) Printed 3 February 2010 (MN LATEX style file v2.2)

    E-Print Network [OSTI]

    Evans, Dan

    February 2010 (MN LATEX style file v2.2) High resolution X-ray spectroscopy and imaging of Mrk 573 Stefano Astronomico di Roma (INAF), Via Frascati 33, I-00040 Monte Porzio Catone, Italy 3 February 2010 ABSTRACT We et al. 2003; Bianchi et al. 2006). Since the NLR is also believed to be #12;2 Stefano Bianchi, et al

  3. Scanning tuneeling microscopy studies of fivefold surfaces of icosahedral Al-Pd-Mn quasicrystals and of thin silver films on those surfaces

    SciTech Connect (OSTI)

    Unal, Baris

    2008-12-01T23:59:59.000Z

    The present work in this dissertation mainly focuses on the clean fivefold surfaces of i-Al-Pd-Mn quasicrystals as well as the nucleation and growth of Ag films on these surfaces. In addition, Ag film growth on NiAl(110) has been explored in the frame of this dissertation. First, we have investigated the equilibration of a fivefold surface of icosahedral Al-Pd-Mn quasicrystal at 900-915 K and 925-950 K, using Omicron variable temperature scanning tunneling microscope (STM). Annealing at low temperatures resulted in many voids on some terraces while the others were almost void-free. After annealing at 925-950K, void-rich terraces became much rarer. Our STM images suggest that through growth and coalescence of the voids, a different termination becomes exposed on host terraces. All of these observations in our study indicate that even after the quasicrystalline terrace-step structure appears, it evolves with time and temperature. More specifically, based on the STM observations, we conclude that during the annealing a wide range of energetically similar layers nucleate as surface terminations, however, with increasing temperature (and time) this distribution gets narrower via elimination of the metastable void-rich terraces. Next, we have examined the bulk structural models of icosahedral Al-Pd-Mn quasicrystal in terms of the densities, compositions and interplanar spacings for the fivefold planes that might represent physical surface terminations. In our analyses, we mainly have focused on four deterministic models which have no partial or mixed occupancy but we have made some comparisons with an undeterministic model. We have compared the models with each other and also with the available experimental data including STM, LEED-IV, XPD and LEIS. In all deterministic models, there are two different families of layers (a pair of planes), and the nondeterministic model contains similar group of planes. These two families differ in terms of the chemical decoration of their top planes. Hence, we name them as Pd+(with Pd) and Pd-(without Pd). Based on their planer structure and the step height, it can be said that these two families can be viable surface terminations. However, besides the Pd content, these two sets differ in terms of relative densities of their top planes as well as the gap separating the layer from the nearest atomic plane. The experimental data and other arguments lead to the conclusion that the Pd- family is favored over the Pd+. This has an important implication on the interpretation of local motifs seen in the high resolution STM images. In other words, the dark stars are not formed by cut-Bergmans rather they are formed by cut-Mackays.

  4. Fabrication of p-{beta}-Fe{sub 1{minus}x}Mn{sub x}Si{sub 2}/nSi heterostructure diode and their electrical and optical properties

    SciTech Connect (OSTI)

    Takada, T.; Katsumata, H.; Makita, Y.; Kobayashi, N.; Hasegawa, M.; Uekusa, S.

    1997-07-01T23:59:59.000Z

    The authors report on the fabrication of p-type {beta}-FeSi{sub 2} layers on n-type Si(100) substrates and the investigation of their p-n diode characteristics. Since the undoped {beta}-FeSi{sub 2} layers have typically shown n-type conductivity, the p-type layers were formed by the introduction of Mn impurity into {beta}-FeSi{sub 2} layers using two types of doping methods; one is an Electron-Beam-Deposition (EBD) procedure of Fe{sub 1{minus}x}Mn{sub x}Si{sub 2} (x < {approximately}0.1) at room temperature and subsequent annealing at 900 C for 1--120 min, where FeSi{sub 2} ingots added with Mn({approximately}10%) were used as starting materials. The other is a {sup 55}Mn{sup +}-implantation into {beta}-FeSi{sub 2} layers formed by EBD and subsequent annealing at 850 C for 1--120 min. From van der Pauw measurements, p-type {beta}-Fe{sub 1{minus}x}Mn{sub x}Si{sub 2} layers with the resistivity of 0.0036--0.031 {Omega}{center{underscore}dot}cm and hole mobility of 11.9--89.0 cm{sup 2}/V{center{underscore}dot}sec were found to be successfully formed on n-Si substrates by both doping methods. The p-n diode characteristics of these heterostructure diodes were investigated by I-V and C-V measurements. The results indicate that the carrier distribution does not agree with either ideal one-side step or one-side slop junctions, although optical transmittance and reflectance measurements indicate that the silicide/Si interface is of good quality.

  5. Efficient spin transfer torque in La{sub 2/3}Sr{sub 1/3}MnO{sub 3} nanostructures

    SciTech Connect (OSTI)

    Foerster, Michael [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz (Germany); ALBA Synchrotron light source, Carrretera BP 1413, km 3.3, 08290 Cerdanyola del Valles, Barcelona (Spain); Peña, Luis; Finizio, Simone; Schulz, Tomek; Bisig, André [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz (Germany); Vaz, C. A. F. [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz (Germany); SwissFEL, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Heinen, Jan [Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz (Germany); Büttner, Felix [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, 55128 Mainz (Germany); Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Eisebitt, Stefan [Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Méchin, Laurence [GREYC, UMR 6072, CNRS-ENSICAEN-UCBN, 6 Boulevard du Maréchal Juin, Caen Cedex 14050 (France); and others

    2014-02-17T23:59:59.000Z

    We carry out low temperature magnetotransport measurements on nanostructured La{sub 2/3}Sr{sub 1/3}MnO{sub 3} wires to study the interaction between spin-polarized current and magnetization in this half metallic material. We selectively position domain walls by applying external fields. The domain wall resistance is found to be positive, in contrast to conventional 3d metals. The depinning field is reduced when current pulses are injected into the wire. By comparing measurements for both current polarities, we can disentangle heating and spin transfer torque effects. The determined spin transfer torque efficiency is of the order of 4?×?10{sup ?14} Tm{sup 2}/A, which is significantly higher than in permalloy.

  6. Electrical stability of a novel sealing glass with (Mn,Co)-spinel coated Crofer22APU in a simulated SOFC dual environment

    SciTech Connect (OSTI)

    Chou, Y. S.; Stevenson, Jeffry W.; Xia, Guanguang; Yang, Zhenguo

    2010-09-01T23:59:59.000Z

    A novel alkaline-earth silicate (Sr-Ca-Y-B-Si-Zn) sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was sandwiched between two metallic interconnect plates and tested for electrical stability in dual environmnet at elevated temperatures of 800-850 degrees C. A ferritic stainless steel (Crofer22APU) was used as the metallic interconnect material in the as-received state and coated with (Mn,Co)3O4 spinel. The isothermal aging results showed stable electrical resistivity at 800-850 degrees C for ~500-1000 hr. The electrical resistivities at 800 or 850 degrees C of the spinel-coated samples were lower than the as-received ones; however, they were still several orders of magnitude higher than typical SOFC functional parts. Interfacial microstructure was characterized and possible reactions are discussed.

  7. 15N2 formation and fast oxygen isotope exchange during pulsed 15N18O exposure of MnOx/CeO2

    SciTech Connect (OSTI)

    Kwak, Ja Hun; Szanyi, Janos

    2014-12-23T23:59:59.000Z

    Pulsing 15N18O onto an annealed 1% Mn16Ox/Ce16O2 catalyst resulted in very fast oxygen isotope exchange and 15N2 formation at 295 K. In the 1st 15N18O pulse, due to the presence of large number of surface oxygen defects, extensive 15N218O and 15N2 formations were observed. In subsequent pulses oxygen isotope exchange dominated as a result of highly labile oxygen in the oxide. We gratefully acknowledge the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy/Vehicle Technologies Program for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  8. Effect of substitution of In for Co on magnetostructural coupling and magnetocaloric effect in MnCo{sub 1-x}In{sub x}Ge compounds

    SciTech Connect (OSTI)

    Wu, R. R.; Bao, L. F.; Hu, F. X., E-mail: fxhu@iphy.ac.cn, E-mail: hufx@g203.iphy.ac.cn; Wang, J.; Zheng, X. Q.; Liu, Y.; Sun, J. R.; Shen, B. G. [Beijing National Laboratory for Condensed Matter Physics and State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-05-07T23:59:59.000Z

    Effect of replacement of Co by In with larger atomic radius but fewer valence numbers on magnetostructural coupling and magnetocaloric effect is studied in MnCo{sub 1-x}In{sub x}Ge compounds. The substitution of Co by a small amount of In (1.5%–2%) can shift martensitic transformation T{sub stru} to lower temperature and make it overlap with Curie temperature T{sub C}. As a result, magnetostructural coupling is created and large entropy change (?S) takes place. Further increasing In content to x?=?0.03 leads to decoupling, but the martensitic transition (T{sub stru} ? 249?K) is still close to the magnetic transition (T{sub c}{sup A}???269?K). As a result, two close ?S peaks appear. Mechanism related to different large entropy change in the coupled and decoupled samples are discussed.

  9. Anisotropic magnetoresistance of epitaxial Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} film

    SciTech Connect (OSTI)

    Chen, X. G.; Yang, Y. B.; Wang, C. S.; Liu, S. Q.; Zhang, Y.; Han, J. Z.; Yang, Y. C. [State Key Laboratory of Mesoscopic Physics, and School of Physics, Peking University, Beijing 100871 (China); Yang, J. B., E-mail: jbyang@pku.edu.cn [State Key Laboratory of Mesoscopic Physics, and School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

    2014-01-28T23:59:59.000Z

    The magnetic field and temperature dependent anisotropic magnetoresistance (AMR) of the epitaxial grown Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} thin films was investigated. It was found that the magnetoresistance exhibited the characteristics of magnetic polaron hopping. A two-fold symmetric AMR occurred in the ferromagnetic region (?220?K?

  10. Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La{sub 0.5}Ca{sub 0.5}MnO{sub 3} nanoparticles

    SciTech Connect (OSTI)

    Iniama, G.; Ita, B. I. [Department of Pure and Applied Chemistry, University of Calabar, Calabar (Nigeria); Presa, P. de la, E-mail: pmpresa@ucm.es; Hernando, A. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Físicas, Dpto. Física de Materiales, Univ. Complutense de Madrid, 28040 Madrid (Spain); Alonso, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Instituto de Ciencia de Materiales, CSIC, 28049-Madrid (Spain); Multigner, M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Cortés-Gil, R.; Ruiz-González, M. L. [Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain); Gonzalez-Calbet, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain)

    2014-09-21T23:59:59.000Z

    In this paper, the physical properties of half-doped manganite La{sub 0.5}Ca{sub 0.5}MnO{sub 3} with crystallite sizes ranging from 15 to 40?nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15?nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22?nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15?nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.

  11. Exchange bias induced by the fully strained La{sub 2/3}Ca{sub 1/3}MnO{sub 3} dead layers

    SciTech Connect (OSTI)

    Xie, Q. Y. [National Lab of Solid State Microstructures, Department of Physics, Nanjing University, Nanijng 210093 (China); College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Wu, X. S., E-mail: xswu@nju.edu.cn [National Lab of Solid State Microstructures, Department of Physics, Nanjing University, Nanijng 210093 (China); Gao, J. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Jia, Q. J. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

    2014-05-07T23:59:59.000Z

    A pure compressively strained La{sub 2/3}Ca{sub 1/3}MnO{sub 3} (LCMO) dead layer grown on (001)-oriented LaAlO{sub 3} substrate can show all the rich phenomenon of large bias field shift, coercive field enhancement, and high blocking temperature. The obtained exchange bias field (?350?Oe) and the enhanced coercivity of about 1160?Oe at 5?K under 500?Oe cooling field are superior to that have been reported in LCMO-based ferromagnetic/antiferromagnetic superlattices or nanoscale systems. Our results clearly demonstrate that the inhomogeneous magnetic dead layer of LCMO can induce a strong exchange bias effect, which may be exploited as a very simple structure for spin-valve device application.

  12. 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer spin valve component investigated by polarized neutron reflectometry

    SciTech Connect (OSTI)

    Callori, S. J., E-mail: sara.callori@ansto.gov.au; Bertinshaw, J. [School of Physics, The University of New South Wales, Sydney, New South Wales 2052 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Cortie, D. L. [The Institute for Superconducting and Electronic Materials, The University of Wollongong, Wollongong, New South Wales 2522 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Cai, J. W., E-mail: jwcai@aphy.iphy.ac.cn; Zhu, T. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Le Brun, A. P. [Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Klose, F. [Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

    2014-07-21T23:59:59.000Z

    We have observed 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer system using polarized neutron reflectometry. Magnetometry results show magnetic switching for both the biased and free NiFe layers, the latter of which reverses at low applied fields. As these measurements are only capable of providing information about the total magnetization within a sample, polarized neutron reflectometry was used to investigate the reversal behavior of the NiFe layers individually. Both the non-spin-flip and spin-flip neutron reflectometry signals were tracked around the free NiFe layer hysteresis loop and were used to detail the evolution of the magnetization during reversal. At low magnetic fields near the free NiFe coercive field, a large spin-flip signal was observed, indicating magnetization aligned perpendicular to both the applied field and pinned layer.

  13. In situ atomic force microscope study of high-temperature untwinning surface relief in Mn-Fe-Cu antiferromagnetic shape memory alloy

    SciTech Connect (OSTI)

    Wang, L.; Cui, Y. G.; Wan, J. F.; Rong, Y. H.; Zhang, J. H.; Jin, X.; Cai, M. M. [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)] [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-05-06T23:59:59.000Z

    The N-type untwinning surface relief associated with the fcc {r_reversible} fct martensitic transformation (MT) was observed in the Mn{sub 81.5}Fe{sub 14.0}Cu{sub 4.5} antiferromagnetic high-temperature shape memory alloy (SMA) by in situ atomic force microscopy. The measured untwinning relief angles ({theta}{sub {alpha}} Double-Vertical-Line {theta}{sub {beta}}) at the ridge and at the valley were different, and both angles were less than the conventional values. The surface relief exhibited good reversibility during heating and cooling because of the crystallographic reversibility of thermal-elastic SMAs. Untwinning shear was proposed as the main mechanism of the N-type surface relief. The order of the reverse MT was discussed based on the experimental measurements.

  14. Rare?Earth?Free Permanent Magnets for Electrical Vehicle Motors and Wind Turbine Generators: Hexagonal Symmetry Based Materials Systems Mn?Bi and M?type Hexaferrite

    SciTech Connect (OSTI)

    Hong, Yang-Ki [University of Alabama] [University of Alabama; Haskew, Timothy [University of Alabama] [University of Alabama; Myryasov, Oleg [University of Alabama] [University of Alabama; Jin, Sungho [University of California San Diego] [University of California San Diego; Berkowitz, Ami [University of California San Diego] [University of California San Diego

    2014-06-05T23:59:59.000Z

    The research we conducted focuses on the rare-earth (RE)-free permanent magnet by modeling, simulating, and synthesizing exchange coupled two-phase (hard/soft) RE-free core-shell nano-structured magnet. The RE-free magnets are made of magnetically hard core materials (high anisotropy materials including Mn-Bi-X and M-type hexaferrite) coated by soft shell materials (high magnetization materials including Fe-Co or Co). Therefore, our research helps understand the exchange coupling conditions of the core/shell magnets, interface exchange behavior between core and shell materials, formation mechanism of core/shell structures, stability conditions of core and shell materials, etc.

  15. Control of the Magnetic and Magnetotransport Properties of La0.67Sr0.33MnO3 Thin Films Through Epitaxial Strain

    SciTech Connect (OSTI)

    Arenholz, Elke; Takamura, Y.; Chopdekar, R.V.; Arenholz, E.; Suzuki, Y.

    2007-12-20T23:59:59.000Z

    The influence of epitaxial strain, in the form of tetragonal distortions, on the magnetic and magnetotransport properties of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} thin films was studied. The tetragonal distortion (c/a ratio) was modulated through the choice of the substrate, ranging from c/a=1.007 on (001)-oriented (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} substrates to 0.952 on (110)-oriented GdScO{sub 3} substrates. In agreement with previous theoretical predictions, these large values of tensile strain cause the Curie temperature and the saturation magnetization to decrease, alter the temperature dependence of the resistivity and magnetoresistance, and increase the resistivity several orders of magnitude.

  16. CaF/sub 2/:Mn thermoluminescence: a single glow peak not described by 1st or 2nd order kinetics

    SciTech Connect (OSTI)

    Hornyak, W.F.; Levy, P.W.; Kierstead, J.A.

    1984-12-01T23:59:59.000Z

    The thermoluminescence (TL) of CaF/sub 2/:Mn has been studied using photon counting and digital recording. For doses of 10 rad or less the TL glow curves appear to consist of a single glow peak. However, there are indications - which are pronounced at larger doses - that one additional low intensity peak (area less than or equal to one percent) is superimposed on each side of the central peak. The intense peak is not described by 1st or 2nd order kinetics but is well described by the more general kinetics from which these kinetics are derived. These observations, and the results of additional kinetic analysis, demonstrate that retrapping is not negligible and may include all three peaks. In such systems, which are likely to include other dosimeter materials and minerals, peak height will not increase linearly with dose; an important factor for dosimetry and dating applications.

  17. Benzene analogues of (quasi-)planar M@B{sub n}H{sub n} compounds (M = V{sup ?}, Cr, Mn{sup +}): A theoretical investigation

    SciTech Connect (OSTI)

    Li, Lifen; Xu, Chang; Jin, Baokang; Cheng, Longjiu, E-mail: clj@ustc.edu [Department of Chemistry, Anhui University, Hefei, Anhui 230039 (China)] [Department of Chemistry, Anhui University, Hefei, Anhui 230039 (China)

    2013-11-07T23:59:59.000Z

    The stability of M@B{sub n}H{sub n} (M = V{sup ?}, Cr, Mn{sup +}; n = 5–8) is investigated by density functional theory. For n = 6–8, the isomers possess (quasi-)planar local minima showed by geometry optimization at TPSSh/6-311+G{sup **} level. All the optimized structures are thermodynamics stable according to the large HOMO-LUMO gap, binding energy, vertical ionization potential, and vertical electron affinity analysis. The peripheral and central atomic radius fit each other best at n = 7 confirmed by the variation of the binding energy values. The availability of d atom orbitals in M for participation in the ?-delocalized bonding with the peripheral ring leads to the aromaticity of the (quasi-)planar structures and makes them the benzene analogues. This work establishes firmly the metal-doped borane rings as a new type of aromatic molecule.

  18. Dynamic magnetic interaction in La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} heterostructure

    SciTech Connect (OSTI)

    Guo, H. Y. [Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan (China); College of Electronic Information and Business, Qingdao Huanghai University, No. 3111, Linghai Rd., Huangdao District, Qingdao 266427 (China); Lin, J. G., E-mail: jglin@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan (China); Yang, Jan Chi [Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Rd., HsinChu 30010, Taiwan (China); Chu, Y. H. [Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Rd., HsinChu 30010, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 105, Taiwan (China)

    2014-09-15T23:59:59.000Z

    The La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} (LSMO/BFO) heterostructure is studied as probed by temperature-dependent ferromagnetic resonance (FMR). Consistent with the structure analysis, two FMR modes are found for both a single LSMO layer and a LSMO/BFO bilayer grown on DyScO{sub 3}, corresponding to the strained and relaxed phases of LSMO. The FMR linewidth intensity vs temperature curve shows two maxima at 200?K and 140?K in the strained phase of LSMO/BFO bilayer, which is related to the magnetic excitations in BFO. Our results demonstrate a dynamic spin interaction between LSMO and BFO, suggesting an effective route to manipulate the magnetic properties of oxide heterostructures.

  19. Enhanced photoluminescence due to two-photon enhanced three-photon absorption in Mn{sup 2+}-doped ZnS quantum dots

    SciTech Connect (OSTI)

    Subha, Radhu [Department of Physics, Indian Institute of Technology, Madras, Chennai, 600036, India and Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore, 117542 (Singapore); Nalla, Venkatram; Ji, Wei, E-mail: phyjiwei@nus.edu.sg [Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore, 117542 (Singapore); Feng, Xiaobo [School of Physics and Electronic Information Technology, Yunnan Normal University (China); Vijayan, C. [Department of Physics, Indian Institute of Technology, Madras, Chennai, 600036 (India)

    2014-10-15T23:59:59.000Z

    In this work, we have investigated the multi-photon absorption induced photoluminescence in Mn{sup 2+}-doped ZnS quantum dots in the wavelength range 860 – 1050 nm (Near-Infrared Window I). The observed three-photon action cross-section has been compared with the theoretical prediction under four band approximation. An enhancement of four to five orders has been observed in the range from 970 to 1050 nm compared to the theoretical value, which is attributed to two-photon enhanced three-photon absorption. Transient lifetime measurements reveal a lifetime of 0.35 ± 0.3 ms, which is four to five orders higher than other conventional fluorescent probes.

  20. Structural changes and thermal stability of charged LiNixMnyCozO? cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy

    SciTech Connect (OSTI)

    Bak, Seong-Min [Brookhaven National Lab. (BNL), Upton, NY (United States); Hu, Enyuan [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhou, Yongning [Brookhaven National Lab. (BNL), Upton, NY (United States); Yu, Xiqian [Brookhaven National Lab. (BNL), Upton, NY (United States); Senanayake, Sanjaya D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Cho, Sung-Jin [Johnson Control Advanced Power Solution, Milwaukee, WI (United States); North Carolina A& T State Univ., Greensboro, NC (United States); Kim, Kwang-Bum [Yonsei Univ., Seoul (Republic of Korea); Chung, Kyung Yoon [Korea Inst. of Science and Technology, Seoul (Republic of Korea); Yang, Xiao-Qing [Brookhaven National Lab. (BNL), Upton, NY (United States); Nam, Kyung-Wan [Dongguk Univ., Seoul (Republic of Korea)

    2014-12-24T23:59:59.000Z

    Thermal stability of charged LiNixMnyCozO? (NMC with x+y+z=1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time resolved X-ray diffraction and mass spectroscopy (TR- XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygen release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability comparable to the low Ni-content materials (e.g., NMC333 and NMC433) while having a high capacity close to the high Ni-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of layered structure (R3m ) but Co ions prefer to migrate to the 8a tetrahedral sites of spinel structure (Fd3m ) during the thermal decomposition. Such elemental dependent cation migration plays a very important role for the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of Ni- to Mn- and Co- contents. This systematic study provides insight into the rational design of NMC based cathode materials with a desired balance between thermal stability and high energy density